Most days, Dr. SJ goes for a nice long walk with her socially distant friends. She likes to walk. I would take the Gator from my library to the bathroom if I could, but to each his own. A couple days ago, she walked the trails of Tiffany Creek Preserve with a garbage bag in hand.

By the end of the walk, the bag was full. Beer cans, used diapers, lots of formerly-sterile gloves and designer water bottles. It could have been pristine. Instead, it was a dump. The litter didn’t get there on its own.

Today is Earth Day. Today is the 50th Earth Day. You probably weren’t aware of this because it’s no longer a big deal, but it was once.

In the 1960s, environmental destruction was upfront and personal. It was in your face. Los Angeles was shrouded in smog. The Cuyahoga River in Cleveland caught fire. Three million gallons of oil spilled off the coast of Santa Barbara, Calif. New York City dumped raw sewage into the Hudson River. Bald eagles were teetering near extinction in the lower 48 states because of the ravages of DDT. Leaded gasoline poisoned children.

We were shitting up our planet and we knew it because our planet was telling us.

“A lot of people were getting angry about dirty water, dirty air and litter,” said Barbara Reid Alexander, Midwest coordinator for the first Earth Day, in 1970. “People were excited to talk about it.”

Notably, this isn’t the same as Climate Change. We had no misbegotten child turned into a cartoon character to shame us about our carbon footprint, although there is certainly a great deal of overlap with the concerns du jour. But this was about actual hardcore things we could do now, this very minute, to not shit up our environment.

The turnout catapulted environmental issues onto the political agenda. Democrats and Republicans took interest. Legislation followed: the Clean Air Act, Clean Water Act, Endangered Species Act, Marine Mammal Protection Act, Toxic Substances Control Act, Resource Recovery and Conservation Act, National Forest Protection Act, the designation of Superfund sites and the establishment of the Environmental Protection Agency.

As invariably happens, our zeal to do better was often misdirected by regulatory overkill or good ideas that failed to take reality into account. We were recycling demons, told that if we separated bottles and cans, paper and plastic, we could beat back the destruction of the planet. Nobody considered what environmental costs were associated with environmental solutions, and anybody questioning would have been beaten to a pulp by fans of Mr. Natural.

Today the story is different. Fifty years ago, the effects of burning fossil fuels on the atmosphere was only beginning to be understood. Now it is the looming threat to the planet as the earth steadily warms. And only now are people seeing, on a large scale, the consequences: record-breaking heat, floods, intensifying storms, landscape fires in California and Australia, the disappearance of Arctic ice, shrinking glaciers, dying coral reefs. But it has been a slow build to creating a movement with the power and public support that emerged from the first Earth Day.

The issues are bigger and more controversial. One reason is that they are distant from us, beyond our personal reach and perhaps our grasp. But then, the zeal with which we approached Earth Day may have owned America for a decade or so, but where is it now?

“If for the last 50 years you’ve only had white, middle-class, mostly male leadership, it’s very difficult to move beyond that,” Mr. Sandoval said.

“The environmental movement was a victim, in a way, of its own early success,” he added. “They thought they had a model that would last, and they didn’t bother to reach out beyond what is a middle-class, white constituency, and that is not enough people to fight off the kind of attacks that are happening now.”

This was very much a white, middle-class movement. Poor people didn’t care about throwing their garbage to the side of the road. Rich people didn’t spend their time returning cans to the supermarket for the five cent deposit.

And over time, not even white, middle-class people saw the point of it. We learned from watching 60 Minutes that recycling was a sham. After we bundled our newspapers, we watched as the garbageman threw them in the same hopper as the rest of our garbage. And when we took nice long walks at places like Tiffany Creek Preserve and finished out Mountain Dew, we threw it in the bushes because it’s not cute to spend the day holding trash.

So Dr. SJ walked the trails, picked up the litter and filled her garbage bag, which she brought home to be thrown in the back of the garbage truck and magically disappear from our sight.

Earth Day at 50 years isn’t what we thought it would be in 1970.