Population Myths, Trends and Transportation Planning
By Glen Hiemstra, 2003
It is generally agreed that the most predictable aspect of the future is the shape and nature of the population. For example, as we plan for transportation 20 years in the future, we can know that most of those who will be of driving age in 2023 have already been born. Thus we can know with some accuracy how many drivers there might be, thus how many cars, trips, and so on.
“It is generally agreed that the most predictable aspect of the future is the shape and nature of the population.”
Less certain are things like where these drivers will all live, whether driving to work will be as common or as necessary, and the technological, political and social options for transportation available in 2023. Transportation planners know better than most that models can be constructed based on assumptions about all of these factors and then allow a forecast of the number or right turns that may be taking place in a certain intersection at 4:30 PM on some specific day in the future.
Thus we also know that effectively using demographic data is tightly bound with making plausible assumptions about the many factors shaping transportation.
This brief white paper will review several common assumptions about demographics, with the intent to improve our assumption making processes.
Five demographic trends are dominant in the United States.
Aging of the population
Of all the people who ever lived to be 65 in the history of the world, two-thirds are alive today. While it was not unheard of to live to age 65 in earlier times, it was rare. The average age at death in the U.S. in 1900 was 47. Now the average life span is 77. Moreover, a 65-year old can anticipate nearly 20 additional years, on average. The median age in the U.S. population reached an all-time peak of 35 in 2000. It is headed for 42 or older in 2020. When the baby-boom generation begins to turn 65 in 2011, the long anticipated ‘age wave’ begins. Older drivers, older workers, older pedestrians are the future.
Large numbers in generation Y, now reaching adulthood
Generation Y, the ‘dot com generation’ or the ‘millennial generation’ is huge. The baby boom was 76 million strong in the U.S. Generation X, those born between 1964 and 1979 was much smaller, at only 51 million (an astonishing drop). Now, the baby-boom echo is upon us, with the generation born between 1979 and 1994 numbering 60 million and with the leading edge in young adulthood. Thus, the next decade and a half will see large numbers of young drivers and workers, following a period of shortage.
[note: in the original 2003 article I said that GenX was only 17 million in number, when I should have said they were only 17% of the population. Estimates of the size of GenX vary, depending on the time span used, and whether the estimator is discussing births in a given year or current population.]
Significant numbers of first generation immigrants in the current population, particularly Latinos
In 2000 the percentage of foreign-born members of the U.S. population hit 10.4%, up from 7.9% in 1990, and the highest since a century earlier. Half were from Latin America (14 million) while a fourth were from Asia (7 million). Regionally, the West and South absorb more of current immigration than do other regions. But most striking is that the foreign-born population is especially concentrated in metro-areas, with 54% living in nine metro areas with populations of five million or more, compared to 27% of the native-born population.
Revival of Urban Living
The 1990’s saw a continuing trend in geographic movement in which people leave the Northeast, the Midwest stays stable, and people move to the South and West. In addition, central cities and rural areas lose population while metro areas outside central cities gain. Between 1999 and 2000 alone, central cities lost 3.2 million people while suburban and exurban metro areas grew by 3.4 million. This explains why so much traffic has shifted to intra-suburban systems. But beware the permanent trend. Over the next twenty years watch for signs of a return to central cities for living, working and recreation. Economic development, environmental, property value and construction trends favor a re-birth of housing in central cities, combined with work and recreation, the’24/7 city’ as it is called. Such a development will put a higher premium on pedestrian transport, and on efficient within-city transport, as compared to classic commuter traffic.
The impending peak of the U.S. population
This is the shocker. The U.S. population is 290 million and growing. It is common to assume that we will double in size this century. But we will not. The concept of the ‘population bomb’ is so imbedded in our thinking that it does not occur to us that human population growth may end, not because of disaster, but because of other natural processes. It is happening. The U.S. population will peak by 2070 at the latest, most likely by 2050, and perhaps even as early as 2025. Why? Birth rates are falling all over the world, including the U.S. It takes a birth rate (technically a ‘fertility rate’) of 2.1 children per woman to maintain a steady state in the population. All of the former Soviet Union, all of Western Europe, Australia, Japan, Canada, and now the U.S. have birth rates below replacement. (Japan’s population will begin to decline in 2005, while Russia declined by 10 million in the past ten years.) The birth rate in the U.S. is 2.08, Canada is 1.52, and Mexico has fallen from 7 to 2.9 in the past two decades. All countries in the world, save four, have seen declines in birth rates since 1980. Explanation? Improved communication, thus better information about family planning, global economic development and the economic emancipation of women, and improved global health care all work together.
The bottom line: The U.S. population will peak at no more than 430 million, and will possibly peak at more like 325-350 million. Thus, on the realistic planning horizon is the prospect that communities will achieve their maximum size, and then begin a gradual decline.
Glen Hiemstra is a futurist speaker, author, consultant, blogger, internet video host and Founder of Futurist.com. To arrange for a speech contact Futurist.com.
