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The Habitable Planet: A Systems Approach to Environmental Science 

Human Population Dynamics Interview with Martha Farnsworth Riche

Interviewer: Can you tell us about the history of your role in the U.S. Census?

MARTHA: I’m a demographer which means that I study populations and changes in populations. In particular, I study the interaction between population changes and things that at other people care about. It could be the environment. It could be the work force. It could be the economy. It could be society. It can be local as in the United States. Or it can be global.

As a demographer I’m part of a community of social scientists that advises the U.S. Census Bureau on its procedures and on its results. Economists do this. Marketing scientists do this and statisticians as well as demographers. I was appointed by my Association, the Population Association of America, to be one of our representatives advising the Census Bureau. I was appointed for that because I am part of a subset of demographers that use the Census data for my work. That’s pretty much all I use, except for some health related data, to do the kind of work I do. So I knew a lot about what the data meant and I knew a lot about what our needs were that were or were not being met. For example, after the 1980 Census, we had a hard time talking about our growing older population because the Census Bureau only showed data for the population sixty-five and older. That encompasses people over about thirty years and we needed them to break the data down into smaller age groups so that we could analyze it. That’s just a simple thing. As a result when the Clinton Administration came in and they were looking for people to head the Census Bureau, they looked amongst the professional community that had worked with Census Bureau, and my name was put forth.

Interviewer: How did you get interested in demography?

MARTHA: My early degrees were in Economics from the University of Michigan. I found myself drawn to those parts of economics that deal with people. Why are people in the work force? Why are other people not in the work force? Who succeeds? How is human well being measured in terms of economics? Just the whole interaction of people and economics; it was the people part that interested me.

Interviewer: What did you do in the Census Bureau. What was your day to day?

MARTHA: A lot of people ask me why I wanted to go to the Census Bureau in 1994, since the Census wasn’t going to take place until 2000. But, they didn’t understand two things. One – the Census has a fifteen year planning cycle. And the Census actually takes place in year twelve. So I had an enormous influence on the design of the 2000 Census. I made all the major decisions. The other thing is the Census Bureau doesn’t just conduct the Census; it conducts all the major population base surveys in the United States. Most of them are paid for by other agencies. But the Census Bureau conducts them because obviously we have the skills and the knowledge to do so. So we conduct what is my personal favorite survey, the one that I use all the time for my work, it’s called the Current Population Survey. That’s the survey that produces the employment rate every month. Every American knows about it. But they don’t know that in order to determine whether people are really unemployed or just pretending that they are, we have to ask a lot of different questions. We need to ask questions about what kind of job they have. We need to ask questions about how much they make so we can see if unemployment, or the Department of Labor can see if unemployment is affecting people at the bottom of the ladder or middle of the ladder or all above or in every part of the country. And as a result, this survey interviews sixty thousand households a month and produces data that is enormously useful and interesting for all the kinds of things that I look at, whether it’s environment, whether it’s transportation, whether it’s housing, whether it’s work. So that really is what I did on a day to day basis. You can think about it as being a steward, a steward of the Nation’s major data collection statistical enterprise.

Interviewer: Could you then tell me about the sub-sections of the Census Bureau?

MARTHA: The Census Bureau really has three and a half sub sections. We have the Census, which gets to be enormous in the years when we conduct the Census. It’s the Nation’s largest peace time endeavor. And it’s a good size in the other nine years. And then we have the economic data collection. These are all the surveys and Censuses that underlie those data that are called the Gross Domestic Product and all of the related accounts that go with those. Then we have the demographic side and that’s the housing surveys, the health survey, the homeless surveys, and of course the work force surveys, things about families and children. Who is taking care of children if the parents are divorced? How much does it cost to raise a child? The half section is basically the international section and that is funded almost completely by other agencies. But, the Census Bureau gathers what is probably the best set of population statistics for other countries, better even for analyst purposes than the United Nations, or the World Bank. And that’s because this isn’t a political effort. The Census Bureau is hired to get the best figures as possible. The United Nations, World Bank, national governments have an incentive to maybe hold back a bit on the figures they’re giving, whether underestimating or over estimating. So the Census Bureau has this little known but highly reliable set of global population figures.

Interviewer: Can you tell me about your current interests, or your current research?

MARTHA: Well, my interests always relate to connecting programs or policies with people, people who design programs, who design policies. And they often don’t think about who they’re going to do them to or with. Or, look at it from those folks’ perspectives. And that’s really what I do. I’ve worked in the last few years on housing issues, particularly in cities. I am working right now with the U.S. Air Force in relation to a variety of work force issues. And I’ve worked for the Department of Defense in general because, you can’t recruit if you don’t know how your population’s changing. At the same time, you need to know what kinds of workers you need. I work for private companies that want to project what is the likely change in U.S. families in relation to all of our products by, say, race and ethnicity or size of family or where in the country they’re going to be. I’m on the Board of a group called Redefining Progress. And we are very concerned with sustainability issues. And then I work both globally and locally and domestically on issues relating to women.

Interviewer: What are they?

MARTHA: Well, for instance, I’ve been involved with some members of Congress who are concerned about the earnings gap between men and women, that it’s diminished but it hasn’t gone away even though women’s education is now the same as men’s. And the reason is that women bear the brunt of family responsibilities. The U.S. needs policies to address those if we want to have women’s full economic productive power in our economy.

Interviewer: Do you look at data from European countries?

MARTHA: One thing that we’ve been looking at in other countries is an initiative that’s going on in Washington about gathering what we would call progress indicators, indicators of national progress. There are several countries involved, Australia is one of them. The rest of them are mostly in Europethat are way ahead of us in this area. But it’s really designed to judge our government. Are they putting our resources, our policy resources, our financial resources in places that are giving the biggest bang for the buck to the U.S. citizen?

All of those interests may seem diverse, but the same thing happens in all of them. We use the same sets of tools, that’s what demography really is. It’s a set of tools to analyze. And we’re always working with people in other disciplines. And that really requires us to understand where they’re coming from and to agree on common frameworks and on common goals.

Interviewer: What in a nutshell is the fundamental question that the Census answers?

MARTHA: The Census is a unique tool because it counts people and at the same it places them where they live. So it’s got a double purpose. It’s the only kind of survey or data collection enterprise that we or any country has that tells you how many people are where. And the how many and the where are equally important.

Interviewer: Why was it “invented”?

MARTHA: The U.S. has the world’s oldest continuous Census. The first Census was in 1790. It was written into the Constitution. It was one of the big issues about the Constitution. Slavery was the other. The big issue here was how will the small states that were part of the original thirteen not be overwhelmed by the power of the larger states. Obviously, the larger states thought well, we should have more power because we have more people. And the small states said no, you shouldn’t. So the compromise that was worked out was to have a bicameral legislature. As you know, every state has equal power in the Senate. And in the House of Representatives every state has power according to its population. And that was the compromise that created the Census, because how do you know what the population size is? Well, they wrote into the Constitution that every ten years, starting in 1790, we would have a Census. That’s why it’s called the Decennial Census. And the House of Representatives would be reapportioned, that is to the say, the number of seats would be reapportioned after the Census.

What happened to make it easy and politically acceptable to everyone, every time there was a Census, the states that got relatively larger got more seats. No one ever lost. No state ever lost seats. But by 1920, the room was full. They said we simply can’t get more seats in the House of Representatives. The Capitol is already built. We’re not going to build another Capitol. So to add more seats to the states that are larger, we have to take some away. And that was extremely difficult. What happened was that in 1930, Congress refused to reapportion. That was because they didn’t like the new people that had come to America that were responsible for the growing states. These were Eastern Europeans and Southern Europeans who, because they had come after the country had been fully settled, had no more farmland. So they had to get jobs in the growing manufacturing area and that meant in cities. This country was founded on an idea of farmers, citizen farmers. And cities were always seen as bad with revel and populace. The idea was we don’t want to do like they’ve done in the old country/like England, where there were such things as rotten boroughs and mobs were bought; their votes were bought by buying them drinks. So on that basis, there was a philosophical and a cultural worry that states that were full of those nice citizen farmers were going to lose seats to states that had lots of these dirty urban poor. And that’s why they didn’t reapportion in 1930. They did not reapportion until they got immigration under control to put a cap, a ceiling on people coming from countries that were not part of the original U.S. population.

Interviewer: So what did they say was the origin of the U.S. population?

MARTHA: This goes back to the Census Bureau. This was not a fine moment in the Census Bureau’s history when it was asked in the 1920’s to determine what were the national origins of the original U.S. population. The Census Bureau staff had said we could figure out how to do this. But they didn’t reckon with all the names that had been changed when people got here. They thought they were going to go and look at names and say these are English names, these are French names, these are Swedish names, German names. And that proved to be a very unreliable method. As a result, the Bureau was not able to do the job. And a committee of non-measurement professionals from the American Academy of Sciences, mostly political scientists and historians came up with a measure that the Census Bureau was forced to adopt. So it was a very imprecise measure. And it’s a good lesson as to how hard it is to measure what might seem to be a pretty easy thing.

Because English was our language and because our founding population was English, people from other countries, particularly Germany and Scandinavia and the Netherlands as well as the French, who were the primary other immigrants in the early times of the country, they had an incentive to change their spelling, or their pronunciation, or even the name itself to an English name. And as a result, it was really impossible to determine what were the national origins of the population in 1790. Moreover, if they’d gone back to 1790, they would have had an almost all, or heavily English population. And that would have lost the political support for putting these immigration caps on Germans, on Irish, on French and Scandinavians. There’s a very interesting book called How The Irish Became White, which dates back to that time. There were so many Irish in this country by the 1920’s, that to deny their sort of whiteness as had been the case in the late Nineteenth Century when the Irish first came, would have cost enormous political support for this national origins endeavor. Same thing with the Scandinavians, same thing with the Germans, the Scandinavians, the Dutch, they were part of the original founders because they had been parts of early colonies in the United States. And to make everybody be English was going to mean you simply would not have had enough votes to make the change that people wanted, which was to keep out the Eastern Europeans and the Southern Europeans.

Interviewer: So there was a racism that was ingrained?

MARTHA: What we think of now as ethnicity, in those days was really a kind of racism. That was probably hyperbole, but at any rate people had very strong feelings about people from other countries. We had race riots. They were called race riots, and in the Midwest against Germans, against Italians. There’s a very interesting history of all of that. But the moral is that once there was a new kind of people that were coming and who were different from the previous people, then it was comfortable to associate, to let the previous people be part of the broader group of we, Americans.

Interviewer: Why should people care about the Census?

MARTHA: That’s a very good question. In the 2000 Census, we did a number of surveys and listening activities with Americans to find out exactly why they should care about the Census. And we found that most of them did not care about getting another Congressman. This was somewhat amusing because the members of Congress who oversaw our budget and our activities said you should be more patriotic. The Census form should be patriotic and say what a wonderful thing it is. And it was hard to really not tell them that well actually people don’t care about you. What we found that people cared about was what demographers do with the data. Probably the thing they care about most is disaster relief. When there’s a big natural disaster like the earthquake in California back in the 1990’s, I think it was, or the hurricanes in Florida, the relief agencies go straight to the Census Bureau. The Census Bureau right away provides data. How many people per block, including housing unit addresses, because that’s how we do the Census, we do it by having an address list of housing units. How many housing units? Here are the maps. Here’s how many people you should expect to find. This is a very popular use of the Census.

People also like the use of the Census for schools, for figuring out where schools should be or whether we need junior highs or high schools. They like it very much for hospital planning, health care planning, and they also are aware that the government uses the data from the Census for traffic planning. What streets are one way during rush hour to help you get home faster? That’s the sort of thing people really appreciate. Interestingly, all those questions are being removed from the Census now at the request of Congress because Congress wants the Census to purely count and place the people for the purpose of the Census, which is reapportionment. Starting in 2010, actually it started already. We are having a rolling monthly survey now to gather this, the equivalent over ten years of those data about hospitals, transportation, all those things that we had before in the Census. We’re getting more data. We’re getting really twice as much data. And we’re getting it much sooner so it’s more real. Those benefits made it worth people’s while to figure out how to deal with this. What it’s effectively doing is like a cup of water if you had a fountain going into, but you had a hole at the bottom. It’s a constantly replenished pool. We’d take the older years off and put the new ones on. And so it’s a floating picture that’s more imprecise than that point in time, but it’s much more current.

Interviewer: And so how does that work? Will there be a survey coming to us at some point during the ten years?

MARTHA: What’s happening is we’re surveying over the course of ten years twice as many household as would have gotten that long form in the decennial Census, the one that asked all the interesting questions beyond straight population questions. This is conducted nationwide every month, but it’s a rolling sample. At some point, your household will get a questionnaire asking you to be part of this survey.

Interviewer: Do people take that as serious as the ten year Census, because people know that the Census is coming up?

MARTHA: An interesting issue is how to get people’s participation. The original name for this survey was The Continuous Measurement Survey. I asked the staff if somebody comes to my house and it says please give up an hour of your time to answer The Continuous Measurement Survey, why do I care? Let’s get a better name. So it’s now called the American Community Survey, because these kinds of detailed data, as opposed to our large regular national surveys, are what give your community statistics like the Census. This is what lets your community know about unemployment. This is what lets your community know about how many people don’t speak English or how many people are going to work in this direction and that one and how long it’s taking them – a whole host of things that communities might want to do something about.

Interviewer: Just what is demography?

MARTHA: Demography is really the science of studying people or studying populations. In the strictest sense this refers to studying the growth or the decline of populations in terms of people being born, people dying, and then people moving in, or moving away. The Census is really our most important tool because, it tells us we can compare from ten years ago, or twenty years ago or however far back, back to 1790. And we can see where populations have grown, where they’ve declined. We can see was it because they got a lot of young people that they grew or did young people move out and just we had a lot of older people. And how does that interact with how people form families, because the basic unit of demography is on the one hand, the person, but for data collection purposes, it’s really the household, whether it’s a family household, as it most often is, or somebody living alone or people who aren’t related living together. That’s why a housing unit is our basic geographic unit.

Interviewer: Can you talk about the change in the meaning of the word “family” compared tot forty or fifty years ago?

MARTHA: What a family means now has changed quite a bit over the last century. In a way, it’s almost been a U shape because in some sense it is back to what it meant a hundred years ago, in that young adults now seem to be living at home until they get married as they did a hundred years ago. Many are doing that. But we’ve had other changes. For instance, starting in the 1940 Census, we saw that as the Social Security system took hold, elderly people were not as economically dependent on living with a child as they had been in the past. Looking from the 1940 to the 1950 to the 1960 Census, you see that a continued decrease in older people living with a child and a greater increase – an almost universal increase – in older people having a home of their own which we would summarize by saying older people bought privacy with their increased financial retirement security. We look at when people get married, when they buy their houses, how education is helping people or not helping them to have increased incomes relative to their parents, a whole host of factors. Obviously, race and ethnicity is an important thing that we look at. And throughout out history, starting in 1790, almost every Census has had some change in the way we measured our race and ethnicity. These are all bound up with political changes in the country. For instance, in 1790, we had our first Census based on the descriptions from the Constitutional convention; black people were counted as three-fifths of a person. And Native Americans were only counted if they were “civilized.” And by civilized, it meant that they lived in houses with addresses like the rest of us did.

Interviewer: But not all Census are the same. How do you compare a 1910 Census to a 1960 Census?

MARTHA: All Censuses are the same in that they have the same purpose and produce the same results. They count people. And they place them where they live. So this is ongoing. We can compare from Census to Census how many people were in this community since the community has been in existence, which is not since 1790. But, we ask the questions differently according to how other changes are taking place. And that’s what makes it so interesting. It’s an on-going iterative process of change in the population that we have to match and track. Because people are very concerned about comparing from Census to Census, it’s hard to make a change in definition. I’ll give you an example. We made a change a couple of Censuses back in how we defined higher education. Do we ask: Has a Bachelor’s Degree. Or do you say: Has so many years of college? Has four years of post secondary education. People are taking much longer now to get their Bachelor’s Degree. So we basically can no longer assume that four years of post secondary education equals a Bachelor’s Degree. We’ve done some tweaking there. And what happens in a case like that, when you’ve made changes, fundamental changes, is we conduct a lot of surveys around the time of the change so that we can make what we call a statistical crosswalk to knit together the old series and the new one. Sometimes, we can’t do that. And we just have to say sorry.

Interviewer: In a hundred and fifty years, if I come back to the Census conducted in 2000, how would I know that you redefined higher education? Does that exist anywhere as a guide?

MARTHA: Census publications are obviously extensively footnoted, because all of these changes are extremely complex. And believe me, they are commented on extensively by the broad public as well the academic community. They are tested. So when all the tests are available, you can see how things changed. That presented a problem for putting things on the internet. Because on the internet, you can see the data, but you can’t see the footnotes. So an ongoing issue is how to give people the information that they want. In publications it was easy to use a different kind of type face, or what have you. But everybody who looks at these data closely knows that you need to read the footnotes. A major example is the change in race and ethnic measurement that has been going on and will continue to go on. In 2000, for the first time, people were allowed to say they were of more than one race. Up until 2000, we forced people to pick their race. A lot of people picked “other”. And the “other” category was growing and that wasn’t very meaningful for policy purposes. So we did a lot of surveys and found out why people were picking “other.” One of the reasons was that people were reluctant to make a choice. At the same time, there was political agitation going on. I remember a Congressman at the time a lot of this work was going on had a constituent in his district who was part of an interracial couple and was offended that their child should be coming home and saying, “Mom, Dad, I had to pick one of you. And I don’t know which one to pick to say that I am like.” And so there was a lot of political activity around the country. That process of redefining how to ask about race took well over a decade…and I can’t tell you how many pages of comments from all around the country.

Interviewer: I think it’s interesting today that in some countries to ask the question is considered racist, but is it racist not to ask it? Because if you don’t ask, then you can’t identify issues within subsets of communities?

MARTHA: Every country has its own way of looking at certain characteristics like race or ethnicity. They might even look at a residence differently. In France, for instance, all communities that have universities in them want to count the students as part of their populations. Whereas the communities where those students go home want to count those populations, too. We have the same thing in this country but in France, they count both. They make everybody happy. But it means they’ve got double counting. What we all agree on is you’re alive, you’re here, or you’re not here. And I think we all agree on age. We all count age the same way. Past that, there are differences in definition and that makes for very interesting international conferences with our colleagues.

Interviewer: What are some practical uses of demography?

MARTHA: Demography is a very practical discipline. Essentially, we are a bag of tools and methods that we apply to a very concrete subject matter, which is people. People are the focus of policies. They’re the focus of programs. They’re the focus of advertising, entertainment, what have you, but they’re the common denominator. So we, with our practical tool kit, work with people in other disciplines whohave their own agendas. It could be political. It could be economic. And they may have their own ideologies. We don’t have an ideology. We count and we place and we describe. And then we help colleagues who have other purposes make the connection they need to make or they ought to be making with the people that they’re targeting.

I’m currently preparing a paper for the Applied Demography meeting in January called One Among Many. It’s about being the demographer on a multi disciplinary team. What kinds of things need to be in place for us to work productively with the team? Probably the most important thing is the overall work needs to have a clear cut mission or goal. And it needs to have a framework, a theoretical construct that everything fits into, because we can’t work with people who are visioning, or idealizing. We need to get it down to something that we can contribute to.

Interviewer: There must be some demographers who have a political agenda.

MARTHA: You know actually demography is pretty much not political. We can choose what group we want to work with, what projects we want to work on. We may or may not feel comfortable with a given agenda. But, it’s pretty hard to argue about was someone born? did they die? In the past I would have said that it’s pretty hard to argue with are they male or are they female? because, of course, gender is another thing that we use as a descriptor. Now that’s a bit up in the air, too. In this country, at least when we come to something that is perhaps not black and white like race, or presumably like gender for some people, we rely on self reporting. We ask people, “What are you? What is your race? Are you male or female?” And we don’t go and check their birth certificate when we ask them how old they are. We take their word for it. So it’s self reporting. We ask the questions. People report to us the answers. And we have learned over decades of surveys and tests that we get better data if we let people describe themselves as they see themselves rather than trying to force them into boxes.

Interviewer: Is there a way of testing the accuracy of the reporting?

MARTHA: What we will do is conduct a small test survey at the same time as we’re doing our larger Census, or a larger sample survey. We’ll do that with interviewers, very highly trained skilled interviewers, usually older, middle class women, who somehow seem to be very good at eliciting answers from people. They’ll go and talk to people and make sure that what people are writing down in their questionnaires is exactly how people see the truth. It isn’t our business to judge the truth – just counting. We can count. There has been a bad history of asking our interviewers or enumerators to make a judgment. For instance, in the early part of the twentieth century, the latter part of the nineteenth century, census interviewers were instructed to describe the degree of a person’s mixed race. Were they an Octoroon? Were they a Quadroon? Were they a Mulatto? This is all done visually. There’s too much room for bias here. That’s another reason that we conduct these sort of special very intensive tests to make sure that we’re not interjecting bias.

Interviewer: Why is the Census conducted every 10 years?

MARTHA: A census doesn’t have to be every ten years. In other countries there are different cycles. And I really can’t tell you why the Founding Fathers hit on ten years, but they did. That’s what’s in the Constitution. It may well have been to get away from the political cycle, because a Presidency is every four years. So this means that every other Census coincides with the Presidential election. But every other one does not. That said, because the country is so politically divided now, many states are trying to reapportion and redistrict. Many states are trying to redistrict inside the ten year cycle so that a party in power can increase the number of its seats in a particular state. But nationally the reapportionment between states is every ten years and that is written in stone. Other countries have different rhythms. The United Nations has taken the lead in trying to get every country to conduct their Census in a year ending in 0 or one, so that we can have more comparable international data.

There’s an interesting mix of what the states can do versus the Federal government. But the bottom line is one person, one vote. This was upheld by the Supreme Court in the 1960s because that 1930 change in the Census that I mentioned earlier removed what had been a part of the Federal law on reapportionment to say that reapportionment should be representative or redistricting should be representative within a state. And as a result, as the country went from agricultural to urban, in many states the rural farm districts kept their seats and made sure the city didn’t get full representation. I come from Michigan. Detroit had just a couple of seats compared to seats in the agricultural parts of the state. As a result, the state’s delegation was extremely unrepresentative. And this happened in other states. There were court cases on it that reached the Supreme Court in the 1960s. And the Supreme Court came down with what is usually referred to as the one man, one vote decision. Essentially it says that a Congressional District should be roughly equal in population size. And that they should be contiguous. Now if you’ve ever seen some of the maps of Congressional Districts in the United States, you’d know that contiguity theme, it’s called gerrymandering, after Elbridge Gerry who, in Massachusetts in the Nineteenth Century, created a district that looked like a salamander. That still goes on. It still goes to court and it’s really where the envelope is constantly pushed. Now some states – Iowa I think was the notable example – have said let’s not let the politicians skew this. Let’s have something more sensible. And they’ve created an independent board, sometimes more judges, sometimes more citizens, but at any rate, an independent, non-partisan board that creates the seats. And you don’t find those funny looking districts in those states.

Interviewer: How is contiguous defined?

MARTHA: One of the things that happens in this measurement business is that we are constantly having to redefine as circumstances changes. For instance, what is contiguous in a Congressional District might be different in a time of urbanization compared to a time when people were on farms. We are constantly defining things like what is a family in measurement terms. For instance, we now define a family as blood relatives living under the same roof. Well, what does that mean to a child whose parents are divorced and live some place else? It makes the parent the child lives with a single parent, but the child actually has two parents. Or if the child goes to both parents, lives with both parents, the child is arbitrarily assigned to one because of this placing and measuring business. In Canada there’s been a proposal to redefine family as people who are related by blood and who interact with one another, say, for caretaking but you don’t necessarily have to live together.

I have many colleagues who are researching how do we define a family. We know how to define it by blood. But if you never see a lot of these people, is this effectively your family? So one thing my colleagues are looking at is the amount of interaction. It could be interaction spending time. It could be interaction of care or it could be interaction through transferring money. What direction?

Interviewer: How long does it take from when you finish the Census for the data take to you to the point where you can redistrict?

MARTHA: The law mandates that the President and the Congress get the population data of each state they need for reapportioning by December thirty-first of the year in which the Census is conducted. It takes longer obviously to get the more detailed data for drawing the new district lines. But that, I think, is due by April – in other words, within three hundred and sixty-five days of conducting the Census. As our population gets bigger and Census taking is more complex, we have to constantly invent ways to make the system efficient so we can meet those deadlines. Probably the most notable example was the 1890 Census where an employee named Herman Hollerith invented something called the Hollerith punch card so we could tabulate the data from the 1880 Census. It took almost the entire decade to get the data fully tabulated because they were doing it all by hand.

Interviewer: Can you talk about the accuracy of the Census and trends in some dynamic populations?

MARTHA: Some countries, in order to get an accurate Census, make everybody “stand still.” They’ll take a day. Everybody stays at home and you have a curfew and then they’ll have the Army go around and count all the people. I don’t think Americans would stand for that. And so, as a result, we have a problem of getting everybody counted on the same day, which is April 1st. People don’t stand still. Babies get born. People die. People move. And oddly enough, not everyone sends their Census form back accurately filled out as to where they lived on April 1st. So we have a number of procedures and policies to get around this inevitable liquidity in the population. Obviously, on April 1st some people might be in a van driving across country. We’re probably going to miss them. But what we don’t do is go person to person. Most people think that’s what we do. We don’t do that. Our Census is based on the address list of housing units. We spend a great deal of time every year, not just in the Census year, getting this address list accurate. New houses are built; houses are demolished. Units are changed from one unit into two, or vice versa. So this requires a lot of collaboration with local government around the country. And this is an ongoing process. Starting with the 1980 Census, we turned this address list into a computerized map. It’s called Tiger – Topologically Integrated Geographic Encoding and Referencing system – and it’s essentially the basis for all of the geographic tools that you see on the internet because it was the first computerized street map of the United States. People who wanted to develop other products could buy that map from us and extend onto it. But essentially what we have is a computerized street and road map of the United States where we pinpoint every housing unit. That’s what we call our frame for the Census. What we need to do is to get an answer of how many people live in each of the units at each of these addresses.

What we’re doing is getting a check on every housing unit in America and how many people are living there. That’s really the way we work at accuracy. Now you can imagine, not everybody’s above board. In a place like Los Angeles, or in a neighborhood where you’ve got a lot of immigrants, someone might have taken a garage and turned it into an illegal housing unit and they’re not going to want to tell you that it’s an illegal housing unit. But we do walk the streets. We work closely with the local officials to try to identify every housing unit. That said, there still are places where there’s a house where we know there’s somebody living there because lights go on and off. And there’s mail. The postman says yes, people are picking up the mail. But people never come to the door or are never home when we come. After a while we run out of time. We’ve got ten weeks to do all of this. And there are people who, willfully or not, just don’t want to make contact with us. What we do then is we say this is not a vacant unit. This is an occupied unit and the computer will drop it into the database. It will drop in the population results for the previous unit counted in that neighborhood in that block on that street. And so if those people had three children and you only have two, well, you’re going to have three children, or your unit will. It’s not attached to your name because remember you didn’t send us anything. You didn’t talk to us. We don’t know who you are. You’re descendants will not be able to trace you some years hence when the data are made available. But the computer has counted you. Because our job, and a lot of people don’t agree with this, our job is to count the population of the United States and that’s what we do. So we get the best estimate possible. It still is an estimate. We conduct a large sample survey, a very intensive sample survey at the same time as the Census is going on. This is done with personal interviewers who are skilled, trained; they do this every month, every year. And we get these much more solid results so we compare the two. And that gives us an estimate as to how accurate the Census is.

Interviewer: Is there an illegal penalty for not sending it in?

MARTHA: Your response to the Census is required by law. We put this on the Census form. Some members of Congress are sure that this encourages some people in not responding. They don’t want us to put it on. But we’ve tested that. We’ve tested pretty much everything that Congress has ever suggested. And it turns out that we get much better, more accurate, and less costly responses if we put that on the form. So we do. That said, we’ve never sent anyone to jail.

Interviewer: This county has been built on immigration. And there’s still a lot of immigration happening. Between one census and another, is there a difference in the type of people that you’re measuring?

MARTHA: That’s right. But the Census is just a snapshot at a point in time. We don’t say where were you ten years ago and then go back and match that record. Remember we’re going to a housing unit. We don’t know necessarily that you aren’t the people that were there ten years ago. We have this housing unit. You were at Nine Main Street. We were counting you today because you’re at Nine Main Street. But ten years ago, someone else may have lived at Nine Main Street. We don’t ask, “Golly, you’ve got three kids now and you had four then. What happened to the other one?” We’re not asking you that because it’s not our business. We’re asked only to count the U.S. population at a point in time. So thinking in terms of population dynamics, what are the things that make the population grow or decline, either overall or in various places – we aren’t really the place to go to get that information. That has to come from surveys. In addition, we’re missing one important piece of the basic population dynamics. Populations, as you know, grow because people are born. They decline because people die or leave. Or, as in our case right now, they’re growing because people are dying later, or aren’t dying at the rate that they used to. They also grow because immigrants come. And they decline because people leave. In this country, we don’t measure immigration. So we don’t know how many people have left. That’s the reason that we can’t just use birth certificates, death certificates, and immigration data to measure our population because we don’t have the immigration part.

Some people think we should be measuring only American citizens. Why are we counting the population? We should be asking are you a citizen or not – not measuring if you’re not a citizen. This is a perennial issue. The Constitution says we will count the American population. The American population is everyone who is living here because they have to be governed. They could be here just as tourists for a week. Or they could be here as students for two years, or as immigrants for five years. That’s not the issue. We count the population. Moreover, we’ve learned from experience that if we ask people if they are citizens, we will have less accurate population data, because some people are not going to answer the question correctly.

Interviewer: What happens to homeless people on the streets?

MARTHA: The homeless population is certainly a problem to count. And we haven’t come up with a good way. We tried in the last Censuses to improve our counting of the homeless population. We’ve had a particular night where we work with shelter providers and other people who work with the homeless population to go out and go under bridges where homeless people are known to gather and to count them. We’ve worked with people at soup kitchens and places where the homeless people receive services to count them. And we’ve done our best but the fact of the matter is that our population count is based on counting housing units, including counting housing units of say dormitories, or prisons, or hospitals, or nursing homes. For people who don’t have housing, they automatically fall between the cracks. We make an attempt, a really large and expensive and good faith attempt, to count that population. But we don’t have anything to check it against the way we do with our address register. Short of heat sensing tools, I don’t know how we could really do it.

Interviewer: Can you give us an idea of the populations in the past, now, and in the future?

MARTHA: George Washington wrote, I think it was to Benjamin Franklin, our ambassador to Paris, about the results of the Census. And he said we are about four million people. I think we were really more, but we know that many people would not answer, some because it was against their religion, others because they thought it was none of the government’s business. And I don’t think that’s really changed that issue of accuracy. But we are more accurate now. We just recently hit three hundred million people. So that gives you an idea. Four million in 1790. Three hundred million in 2006. Our population is growing at less than one percent a year, which is a much lower growth rate than we had in the early years. We are pretty much the only industrialized country that is seeing significant population growth. People think that it’s because of immigration. Immigration accounts for maybe half of our annual population growth. Other people think it’s birth because we have a higher fertility than other industrial countries. But we’re actually just replacing ourselves through birth. Probably, the primary driver of our population growth is that we aren’t dying as young as we used to. That three hundred millionth person that the newspapers were trying to trace down, thinking that it was a baby born – it wasn’t a baby born. It was someone who died on a Wednesday instead of Tuesday. That was our three hundred millionth person. And that’s a major source of our population growth – our life expectancy is growing. So put that together with the fact that we are simply continuing to replace ourselves. We’re staying stable through our births, our population is aging. Our average age was thirty-three in the 2000. That was the oldest we’ve ever been and we’ll never be this young again. That’s the direction our population is going. I heard someone saying today that in the past our population has been like a baby or a teenager. We are now entering the mature adult stage of our population life with more and more of our population being middle aged and older people.

Interviewer: Do you have any predictions for the future trends?

MARTHA: How much our population continues to grow is probably dependent on immigration. Obviously, we’re not going to stop having improvements in health if we can help it. No one’s saying we need to keep dying at the same age. So we should continue to get slow population growth due to living longer. And I don’t see too many reasons for us to have our population decrease through fewer births the way countries like Germany and Japan and other countries are because we are really paying attention to the kinds of policies that are needed to help people have as many children as they want. And people keep on saying I want two kids. As a country, the U.S. is continuing to act on helping to facilitate that. It could do some more childcare, could do more family friendly policies. But, I think, by and large, we’re doing a good job. And that’s why we’re the only country that really is continuing to have replacement level fertility. The wild card is immigration. Almost half of our population growth is coming from immigration. That, as you know, is a major political sore point. The current administration has tried to pass immigration legislation. There is not a consensus in the country as to which way to go. That said, the push pull factor is such that as long as we have rapid population growth in countries that cannot employ all their people, we will have people coming to this country. An interesting older example is Ireland. Throughout the twentieth century, we had a large inflow of Irish immigrants into this country because Ireland’s economy simply couldn’t employ all of their young people. In the latter part of the Twentieth Century, Ireland joined the European Union. Technology changed. Communications changed. Now the Irish in America are moving back home. And that’s the first in over a hundred years. When we see Indians moving back to India, as we already are seeing, when we see Mexicans moving back to Mexico because the jobs are better, when we see people moving back to Africa and Latin American, that’s really when we’ll see immigration decline. But we have many parts of the world where population growth is still so very large, seven, eight, nine children per woman that the countries have no way of employing those people. That says to me that we’ll continue to see pressure for immigration from Africa and particularly from the Middle East.

Interviewer: Can we talk of environmental problems because of our population increase?

MARTHA: Many environmentalists think that population growth is part of the sustainability issue for the United States. That’s a debatable assumption. It really comes back not to how many people but to how they live and to how they use resources. I’ve heard at meetings, where I’ve spoken, environmentalists, usually men, stand up and say no women should be allowed to have children for twenty years because our population is growing too much. In fact one social scientist has calculated that everybody in the world, all six and a half billion people, could live and be sustained in the state of Texas. Now that’s one extreme. I don’t think I’d like to live in the state of Texas with six and a half billion people. It really comes down to how you define sustainability. And that’s a debatable question. One demographer, Joel Cohen from Rockefeller University, a few years ago looked at all the estimates made of population, size, and sustainability, trying to answer the question how many are too many? And it really came down to a huge array of estimates and it depended on what kind of life you wanted. And that’s what really goes into this equation; it’s a matter of trade offs. Certainly in my lifetime, the U.S. population has tripled. Life is very different from the way it was when I was born. I was recently in India. I’ve been in India several times. And, except in tiger refuges, which, by the way, now don’t have many tigers left, but except in nature refuges, there is never a place where you’re out of sight of people. I don’t care how remote in the countryside you are. It’s just a heavily populated country. I understand China is the same way. Population density is the issue. But the fact of the matter is that as we have become healthier over the last half-century, people don’t die in infancy any more. They don’t die in childhood unless it’s a tragic accident. That means, they grow to maturity, even the young people who die of AIDS, they grow to maturity. They grow to have children of their own and that exponentially increases the population. We’re at six and a half billion now heading up to nine billion before we stabilize perhaps by the end of this century. So population growth is heading towards some kind of stability as people replace themselves, but where it’s located and how they consume, that’s the issue for sustainability. Naturally, as our population has grown, it’s put people living and working in areas that might not have been considered salubrious or even viable fifty or a hundred years ago. That’s particularly true in the Sun Belt, the southern part of the country, because that’s where we’ve been moving heavily since air conditioning came into being starting after 1950. We see that in low-lying areas. And New Orleans is a great example. We have people living in places that are inundated by floods, by tornadoes, same thing in Florida. The coast of Texas, we’ve seen all that. Conversely, in the semi arid or arid southwest, we have people using water at unsustainable rates. Why do we have people in Nevada running sprinklers to grow New England gardens? That’s a choice that’s been made. But now we’re coming up against natural limits. And that’s really something that we’re starting to confront in a variety of ways, natural limits for the air, for resources like oil or gas, for water, first and foremost.

Interviewer: How might we mitigate the problems?

MARTHA: It’s consumption, consumption. There are two ways to mitigate these problems that are caused by population pressures. One way is to regulate and control which is something that Americans aren’t very comfortable with. We actually see how that has not worked well in the southern state water compact with the Rio Grande in the west because the politics just get so very difficult, the resolution isn’t very harmonious. Most of us social scientists prefer a market based solution. And that comes from accurate pricing, from having the cost of water reflect its true cost, not having it be almost free to some users. It can be for the cost of clean air. In New York State we suffer from pollution coming largely from Ohio, and from elsewhere in the Midwest, from coal fired electrical plants that don’t give us their electricity, but they send us their carbon dioxide and their soot. They aren’t forced to bear that cost. We are. Getting accurate prices for all of these things is one way; if you have to pay for your fuel consumption by the cost of gas going up, that solution lets you make the choice. And it gets you to a more efficient end than, say, having command and control of things like the auto industry where you say they must get so many gallons per mile.

Interviewer: What are the implications of this research for environmental issues and people’s well being?

MARTHA: We look at migration. We can sort of tell you where people are going so that you can plan. For instance, I think it’s just been in this last month that the suburban population, for the first time in this country’s history, is larger than the urban population. Now if you’re thinking land use planning, if you’re thinking of what people call smart growth strategies, you know that you have different environmental use in the suburbs than you do in the cities. So essentially you might say that what we do is to set benchmarks or announce milestones that trigger peoples’ thinking. This is where our research is going. We can project, for instance, the size of the population. And we can project, based on migration patterns, where this population is likely to be going. If you don’t like what’s happening, then you, the policymaker, or the voter, or the consumer, can make some changes. That’s up to you. We do not make policy prescriptions. But we do tell you, here are the population trends that are happening. They are going to interact with this other factor. It could be land density. It could be water scarcity. It could be a whole host of things. And this is what’s likely to happen unless we change policies.

There was an article recently in the Economist about Youngstown, Ohio. They are talked about as a pioneer, but they’re actually picking up on something Cleveland has done. Its cities and urban areas are recognized as having a population that has declined substantially and it’s not going to come back because the industry that brought them all there is gone. What do we do now? In this case, in Youngstown, and I’ve seen it in Cleveland, they’re taking down vacant and abandoned buildings and turning them into green space. They have a variety of incentives for people to turn them into park land. They’ve changed land use rules to favor rehabilitating old units rather than building new ones and then having older ones go vacant. That’s the sort of thing people are doing in communities that are being abandoned. Communities are vibrant. They grow and they decline usually according to their economies. In New York State, we have beautiful little towns all over central New York that are now full of very reasonably priced lovely old antique homes because the industries that supported those people have moved elsewhere over the last century. At the same time, we’ve got people moving to Tucson, Phoenix, Las Vegas, all those fast growing places. And those places are being stretched by development. Again, if we have accurate pricing of how much it costs to take agricultural land and turn it into housing, if we had a cost benefit analysis, which we really don’t because we’re so fragmented, we might make different decisions. Every day in this country acres of fertile farmland are plowed under for housing. And it’s suburban housing where we’ve got the house and the yard and all that sort of thing. So instead of growing vegetables, we’re growing crabgrass. Is this a trade off that’s valid for those places? Well, those communities have to make their decisions. We’ve seen communities decide that the added population is really not cost effective because the demands for sewers, roads, communication, education, housing, hospitals and so on. It’s really not worth what they’re bringing in, in terms of more taxes.

Interviewer: Do you have any predictions for the future in terms of the environment in this country?

MARTHA: Asking for predictions about the future in terms of environment is really asking what choices Americans are going to make. What priorities are they going to establish. What trade offs are they going to ask for and accept. I think that what’s going on in the Alaska National Wildlife Refuge is a good example. Maybe that’s the canary and the mine. Are we going to demolish an area of pristine national natural beauty that few of us will ever see in order to get a few years more of oil to run our cars and to live our life the way we lead it? My prediction, this isn’t a projection but a prediction, my prediction will be that Americans won’t change their behavior until costs change. And we are very, very good at inventing new ways to do things when costs change. Until those costs change, people think well, golly, if the cost hasn’t changed, well there really isn’t any need for me to change my behavior. I’m only one person anyway. And look how many other millions of us there are. So until we change the cost, until the full and accurate cost of any change of any activity that affects the environment is reflected in the cost that consumers see, I don’t think we’ll change. And the longer we delay on doing that, then eventually the cost will change suddenly and radically and disruptively. Then, we’ll change. That’s one of the choices we have to make.

I’ll give you an example in another area. It’s in health. What would be the single most important thing we could do to reduce the global cost of health care? Stop smoking. Why? Because so many people smoke and the cost of smoking is so great that we multiply the population, the numbers of people times the specific cost. Smoking is far more costly than heart disease or other things that we might think about. We would do the same when we look at transportation and fuel consumption and population. We’ll segment the population by how many are doing this. How many are doing that? Where is the cost coming in? And that enables us to decide priorities for policies. In this community, for instance, we are a small college town surrounded by a semi rural area. We do a lot of driving. But we are just now starting one of these rent a car systems, where people can sign up to rent a car. Those who do prefer to live in town and take public transport or bus, but need a car for some purposes, will now have that rent-a-car they can go to and still have the car. The U.S. has four percent of the world’s population. But we account for twenty-five percent of the emissions of the kinds of gases that are creating global warming. And some of us are embarrassed by that. Others say this is a global problem. We see that large populated countries like India and China, but also Indonesia, Brazil, the former Soviet Union, all are coming on line with their economies beginning to be market economies and beginning to grow and have prosperity and want to consume the way we do. That’s why solving this problem globally has gone past the time when, if the U.S. pulled up its socks, got some self control, and self discipline, we could essentially solve the problem. We can obviously make a difference and certainly with our leadership set an example. All these other countries that would like to be as rich as we are aren’t going to do it voluntarily. But I’d say in the last five or ten years or so, we’ve reached a point where we all have to hold hands and do this together. If you think about the industrialized labor force, the global labor force doubled in the 1990s due to these countries that had had closed and strained economies suddenly becoming market economies. Think about the global labor force doubling and that means global consumers doubling. And if you think about consumers in countries that are just now really getting going, those consumers are going to become richer at a faster rate than we will. They’re trying to come to our level. So we really have increasing consumption in a way that I don’t think people realize yet.

Until people see the cost and the trade offs… I mean I’ve had this argument with environmentalists for years on nuclear power. What I do essentially is give people the base look into the future because we make connections between people and all these things that have costs. You don’t realize this consumption is coming on line. And you’ve got a choice. Do you want dirty coal burning plants? Do you want clean nuclear plants? It’s an either / or.

Series Directory

The Habitable Planet: A Systems Approach to Environmental Science