American environmentalism started as an elite, often unpopular project, but by the late 1960s, concerns about population-fueled ecological catastrophe had become de rigueur. The Sierra Club — the storied environmental advocacy organization founded by Roosevelt’s friend and fellow wilderness explorer John Muir — first took an anti-population-growth stance in 1965. Three years later, the publication of The Population Bomb, biologist Paul Ehrlich’s treatise on the looming “population explosion” and the mass immiseration that would follow, convinced grassroots environmentalists and political leaders alike that overpopulation was the culprit for such varied ills as pollution, crime, and third-world famines. Accordingly, the Sierra Club established a National Population Committee, which in the early 1970s was headed by John Tanton, a small-town Michigan ophthalmologist who moonlighted as the president of his local chapter of the Audubon Society. Tanton had taken Ehrlich’s neo-Malthusian warnings as prophecy, and believed that population control programs were needed to ward off environmental and social collapse. After reading Jean Raspail’s The Camp of the Saints, a 1973 novel that depicted the fall of European civilization through mass immigration from India, China, and various Arab and African countries, Tanton became convinced that the ethnicities of people in the country mattered just as much as the number, if not more so.
The overpopulation frenzy was short-lived, and the movement had splintered by the mid-1970s. Its most hard-line proponents had alienated feminists and people of color by advocating for coercive measures like compulsory birth control and forced sterilization. Even Ehrlich had shifted away from the population argument (perhaps because the cataclysms he predicted hadn’t materialized), and instead began championing a form of environmentalism predicated on reducing the consumptive habits of white middle- and upper-class Americans, rather than on policing the reproductive habits of the world’s poor. Tanton’s focus, however, never wavered from the population issue. He fretted about Mexican women’s supposed hyper-fertility, a topic he claimed was verboten among his peers, and worried that immigrants lacked “respect for the land and our fellow creatures.” Tanton distilled his ideology in an essay for a 1975 contest organized by the Limits to Growth Conference in The Woodlands, a Texas suburb developed by oilman George Mitchell, an overpopulation obsessive who nonetheless had ten children. International migration, Tanton argued, “moves people from less consumptive lifestyles to more consumptive ones,” and therefore needed to be curtailed.