… In December 1970, the acting Surgeon General, in testimony before the House of Representatives, cited “abundant scientific evidence that exposure to polluted air is associated with the occurrence and worsening of chronic respiratory diseases, such as emphysema, bronchitis, asthma, and even lung cancer.”

And yet, while 1970 was not an ideal time for the actual environment, it was something of a golden age for environmentalists. On Jan. 1, 1970, President Richard Nixon signed the National Environmental Policy Act into law. Six months later, he proposed the creation of the Environmental Protection Agency, which opened for business in early December. And on Dec. 31, he capped off the year by signing the Clean Air Act, which was then—and still is—our nation’s most important environmental law. At the signing ceremony, Nixon speculated—correctly—that 1970 would later “be known as the year of the beginning, in which we really began to move on the problems of clean air and clean water and open spaces for the future generations of America.”

Why did all of these green stars align in 1970? For one thing, public interest in environmental issues was growing rapidly. According to nationwide Opinion Research Corporation polls, only 28 percent of the U.S. population considered air pollution a somewhat or very serious problem in 1965; by 1970, that figure had risen to 69 percent.

J. Clarence Davies, a Princeton political scientist who would go on to serve as a senior staffer for the White House Council on Environmental Quality, speculated at the time that heightened concern about environmental degradation was an inevitable product of America’s post-World War II economic boom:

The massive growth in production and in the availability of resources which has characterized the U.S. economy in the past two decades affects the problem of pollution in several ways. The increase in production has contributed to an intensification of the degree of actual pollution; the increase in the standard of living has permitted people the comparative luxury of being able to be concerned about this; and the availability of ample public and private resources has given the society sufficient funds and skilled manpower to provide the potential for dealing with the problem.

In other words, getting rich had come at great cost to the nation’s air and waterways, but, as a result of the nation’s new affluence, Americans were both more inclined to care about improving the quality of their environment and better equipped to succeed in that effort.

The most memorable demonstration of environmental protection’s newfound political salience came in April 1970 when Sen. Gaylord Nelson, a Wisconsin Democrat, and Rep. Pete McCloskey, a California Republican, co-chaired the first Earth Day, a “national teach-in on the environment.” The event drew more than 20 million participants all over the country. The same month, “CBS Evening News” anchor Walter Cronkite, who would soon become known as the “most trusted man in America,” began to include an environment-focused story in each night’s broadcast under the provocative heading “Can the World Be Saved?” ...