The Census Bureau says we'll reach 400 million by 2043, but more reliable predictions suggest we'll add the next 100 million Americans by 2037—that is, in only 31 years.
These figures are from a noteworthy report by Arthur C. Nelson, FAICP, and Robert E. Lang, in the January 2007 issue of Planning, the magazine of the American Planning Association. The authors, co-directors of the Metropolitan Institute at Virginia Tech in Washington, D.C., note that, among industrialized nations, only India will add 100 million people more quickly than the U.S.
Not only is the rate of population growth remarkable, but so too is the composition of this next hundred million. One factor will be the relative importance of single-person households. As Nelson and Lang point out, in 1970, one-person households represented only 17% of U.S. population, while households with children were 44%.
By last October, however, things were already starting to shift. One-person households were now 26% of the population, but “families” had declined to 35%. By the time the next 100 million are in place, the scales could be nearly balanced: 26% one-person households, 27% households with children.
On top of this shift in the composition of households is the aging of the population. In 2006, 29% of Americans were under age 20, 59% were in the 20-64 bracket, and 12% were 65 or older. But in the next 100 million, the biggest group (41%) will be among those of retirement age, with youngsters under age 20 constituting only 19% of the new population and the 20-64 group representing 40%.
As Nelson and Lang note, the demographic shock waves from the next 100 million will have a profound effect on the built environment. By 2037, the U.S. will have to build 70 million housing units—30 million new, 40 million replacement units—to keep pace with the growing population. On the nonresidential side, the authors predict that 30 billion sf of new construction and 70 billion sf of replacement construction will be needed.
One hundred billion sf in new buildings—that's more than the 87 billion sf of existing nonresidential space. In other words, America will have to be completely rebuilt in the next three decades. That's going to require $30 trillion in residential and nonresidential construction and another $5 trillion in infrastructure improvements, the authors say.
This “Second America” will be denser, not just to accommodate the next 100 million, but also because the growing number of older persons in single-person households will want to live in or near cities.
The Second America will have to be greener. Houses and commercial structures will be much more energy- and resource-efficient. Water conservation will be hugely more top-of-mind than it is today. Transportation patterns will shift dramatically.
America's reincarnation has already begun, and the AEC industry is in the thick of it.
America is filling up with people faster than ever. It took 300 or so years, till 1915, to reach our first 100 million, but just 53 years (till 1968) to get to 200 million, and only 39 more—till October 16, 2006, more or less—to top 300 million.