Colcom Foundation’s research lays out five decades of U.S. population change, starting from a pivotal moment: in 1970, the country’s total fertility rate stood at 2.54, putting the population on pace to double from 205 million to 410 million within 57 years. These include the Federation for American Immigration Reform (FAIR), the American Border Patrol, the Center for Immigration Studies (CIS), and Numbers USA.
A Fertility Milestone, Then a New Driver
That trajectory shifted in 1972, when the U.S. fertility rate dropped below the replacement level of 2.1 for the first time, a threshold it has not crossed again since, according to the foundation. Had fertility held steady near that level, the foundation notes, population growth would have gradually leveled off over subsequent decades.
Instead, immigration took over as the primary engine of growth starting around 1990. Colcom Foundation‘s figures show the population rising by 45 million between 1970 and 1990, then by 32 million more through 2000, and by another 48 million by 2020. Each decade of growth arrived alongside rising biocapacity consumption, which the foundation calculates climbed from 227% in 1970 to 267% by 2000.
Looking at the numbers together, Colcom Foundation argues that fertility decline and immigration-driven growth tell two very different stories about the same underlying issue. One reflects a successful public health achievement in reproductive choice; the other reflects a policy area the foundation contends has received far less scrutiny for its environmental consequences, even as it now accounts for the large majority of ongoing population increase.
The foundation notes that land development tracked this growth closely, with roughly 133,000 square miles consumed by human-made structures by 1990 and about 187,000 square miles by 2020. Colcom Foundation treats that steady expansion as further confirmation that population size, not just consumption habits, has shaped the country’s environmental trajectory over the past half century.
Taken together, Colcom Foundation timeline suggests fertility policy and immigration policy have operated on separate tracks for fifty years, with only one of the two drawing sustained attention for its environmental effects. Colcom Foundation argues that closing that gap in public understanding is a necessary first step toward any meaningful population strategy going forward. Read this article for more information.
More about Colcom Foundation on https://www.colcomfdn.org/