U.S. Population Growth
The population of the U.S. has grown dramatically over the course of the last 100 years, from under 80 million in 1900, to nearly 180 million in 1970, to over 280 million in the year 2000. The size and speed of U.S. population growth is of national and global concern for three reasons:
1. The U.S. has a very large population. In terms of total population, the United States is the third largest country in the world, after China and India.
2. The U.S. now has the fastest population growth rate in the industrialized world due to a combination of high fertility and immigration. The population of the U.S. is now growing by nearly 3 million people a year -- the population of Iowa. To put it another way, our population growth rate is faster than that of China, and is about 10 times faster than the population growth rate of Western Europe.
3. U.S. residents have very high per-capita resource use. U.S. residents consume far more resources, and produce far more waste, than people in the rest of the world. The annual addition of 3 million Americans is equal, in terms of resource use, to the addition of 6 million Europeans, or over 36 million people in the developing world.
- Under the Census Bureau's middle series projection, which assumes that current U.S. immigration and fertility levels will stay about the same, the population of the U.S. will increase by 120 million people over the course of the next 50 years.
To put this number into perspective, this is a population equal to the population of every state west of the Mississippi River combined.
- Between 1990 and 2000, the United States added 34 million people to its population -- a population equal to the combined populations of the 20 largest cities in the U.S in 2000 (New York City, Los Angeles, Chicago, Houston, Philadelphia, Phoenix, San Diego, Dallas, San Antonio, Detroit, San Jose, Indianapolis, San Francisco, Jacksonville, Columbus, Austin, Baltimore, Memphis, and Milwaukee).
Under all Census Bureau projections, the population of the U.S. will grow considerably over the course of the next 50 years. The U.S. Census Bureau offers three scenarios for the year 2050. The high and low scenarios are outer-boundary possibilities. The middle scenario is what Census Bureau demographers believe will be closest to what will actually happen unless there are major changes in U.S. birth rates and/or levels of immigrant admissions.
- The Census Bureau's low scenario for 2050 is that over the course of the next 50 years the U.S. will add 35 million people - or a population equal to that of California today. To do that, will require a 75 percent reduction in net immigration to the U.S., and a pretty steep drop in U.S. birth rates.
- The Census Bureau's middle scenario for 2050 is that we will add 120 million people to the population of the U.S. in the next 50 years - a population greater than the entire population of the U.S. west of the Mississippi River today. For this to occur, we will have to hold immigration at current rates, and keep birth rates from rising any further.
- The Census Bureau's high scenario for 2050 is that the population of the U.S. will nearly double. For this to occur, immigration will have to double and then triple (what it has done in the last 50 years) and U.S. fertility rates will have to rise to the level they were in 1967.
Impact of Future U.S. Population Growth
If the population of the U.S. climbs from 283 million in 2000 to 404 million by 2050, as is now suggested by the U.S. Census Bureau's middle-series projections, we can expect to see the construction of about 30 million more housing units than would otherwise have been necessary, assuming average household size stays the same.
What's Driving Growth?
- Immigration: Immigration and the children of immigrants now account for about two-thirds of U.S. population growth.
- Fertility: U.S. fertility rates are about 35 percent higher than those found in Canada and Europe.
- Demographic Momentum: Though the total fertility rate of the U.S. is at "replacement" level, demographic momentum means U.S. population will continue to grow for another 60 years even with zero net immigration.
U.S. population growth is not uniformly distributed across the country. Due to internal migration, differential birth rates, and differential immigrant settlement patterns, some states are experiencing faster rates of population growth than others. Nevada, for example, now has a population growth rate of 4.3 percent a year - a population growth rate faster than that of any country in the less-developed world. Arizona has an annual population growth rate of 2.8 percent - the same as that of Pakistan, Tanzania and Honduras. Colorado's population growth rate is 2.3 percent per year - a rate of population growth equal to that of Ghana and El Salvador, and faster than that of the Philippines. Texas has an annual population growth rate of 1.89 percent per year - about equal to that of Mexico, and faster than that of Lebanon or Indonesia. All of these arid states can expect to see increasing conflict between urban, agricultural, industrial and environmental water needs as human population numbers continue to rise.
From an environmental perspective, here's what 34 million new Americans a decade means:
- Sprawl: Adding 34 million people to the U.S. requires the addition of over 12 million housing units, assuming current U.S. average household size.
- Traffic: Adding 34 million people to the U.S. means adding 15.8 million more passenger cars on America's roads, assuming average per capita car use.
- Oil Consumption: Adding 34 million people to the U.S. increases U.S. oil consumption by about 825 million barrels of oil a year (25 barrels per person per year). To put it another way, 34 million new Americans will consume all of the economically recoverable oil in the Arctic National Wildlife Refuge (ANWR) in less than four years time.
- Wood Consumption: 34 million people can be expected to consume 2.26 billion cubic feet of roundwood per year. Growing this wood will require over 75 million acres of forest in sustainable management.
U.S. Population Policy
In 1972, the Rockefeller Commission on Population Growth and the American Future, released a multi-volume study of U.S. population growth and its impact. The Rockefeller Commission's most widely cited recommendation reads:
"Recognizing that our population cannot grow indefinitely, and appreciating the advantages of moving now toward the stabilization of population, the Commission recommends that the nation welcome and plan for a stabilized population."
Population stabilization recommendations were made by federal commissions during the Carter and Clinton Administrations as well, but little public dialogue about population growth and America's future ensued. The result is that today the U.S. remains without a national population policy.
Values, Goals and Choices
Population growth impacts everything from the construction of water treatment plants to forest fragmentation, from wetlands encroachment to increased crowding of our National Parks.
While it is possible to make a great deal of environmental progress despite population growth, it's also true that rapid rates of population growth make all other environmental protection efforts more difficult. Because public policies governing access to contraception, sex education, and immigration can have a very real impact on U.S. population size, these policies are legitimate environmental issues that need to be discussed within the context of a national population policy.