Chicken Little has always been the press secretary of the environmental movement.

In the 1960’s there was good reason to think the sky was actually falling. The New Yorker published a cartoon showing a wife standing by a table set for lunch in the backyard of a brownstone. “Hurry darling,” she calls to her husband, “Your soup’s getting dirty.” In 1969, the Cuyahoga River that runs through Cleveland was so polluted that it caught fire, not for the first time.

But in 1970, Earth Day was established. It was one of the most remarkable examples of grassroots activism in American history, involving fully 10 percent of the population. Late that year, Congress, at the behest of the Nixon Administration, established the Environmental Protection Agency. A series of acts requiring pollution controls and abatement followed, and the great American clean up began.

How has it worked out? As Investor’s Business Daily reports, the clean up has been a howling success. From 1990 to 2017, the six major air pollutants monitored by the EPA plunged by 73 percent from levels that were already well below 1970 levels. By comparison, during that time, the U.S. economy grew 262 percent and its population expanded by 60 percent. And by 1990, much progress had already been made. Banning lead in gasoline, where it was used as an antiknock agent, beginning in the 1980’s had already greatly reduced the level of atmospheric lead, reducing, in turn, the level found in blood. It is down 98 percent from 1980.

Water pollution has plunged as well, as sewage treatment plants came online. In 1970, Manhattan discharged the sewage of 1.5 million people into the surrounding waterways. Today, there is an annual swimming race around Manhattan. There is even talk of a beach for Manhattan Island, the only borough of New York City without one. This sort of improvement has been duplicated across the country. The Connecticut River, once a 400-mile sewer, is now safe for fishing and swimming along its entire length. Even the Cuyahoga is in much better shape, with riverside cafés looking out over blue water instead of rafts of sludge.

And yet this good news can be hard to find. Government agencies usually are not shy about tooting their own horns when they have success to report. But the pollution history on the EPA’s website is hard to find. And the websites of such organizations as the Sierra Club and the National Resources Defense Council, are still in full the-sky-is-falling mode. I suspect the reason for that has more to do with fundraising strategy than the actual state of the environment.

And even that bugbear of the environmentalist movement, the country’s output of CO2, has fallen 29 percent since it peaked in 2007. That’s thanks largely to the switchover from coal to natural gas as fracking has greatly increased the supply and, thus, lowered the price. Trumpeting that statistic, of course, would not advance the cause of what used to be called “global warming,” and is now called “climate change.”