A few days ago, we published an op-ed about volunteers trying to keep Joshua Tree National Park open during the government shutdown — hauling trash, cleaning and restocking restrooms, staffing an information table outside the closed visitor’s center.

It was an inspiring story about ordinary people stepping up when their elected leaders fell short.

Unfortunately, Sabra Purdy and the other park benefactors failed.

On Tuesday, the National Park Service announced plans to close Joshua Tree, beginning at 8 a.m. Thursday, citing damage caused by visitors to the 790,800-acre desert park in Southern California.

People have started carving their own roads, a spokesman told the Los Angeles Times, and even defacing the park’s namesake trees.

Joshua Tree isn’t the only national park struggling with litter, human waste and vandalism in the 18 days since the partial shutdown of federal agencies started. At Yosemite, the Mariposa Grove of giant sequoias was closed. So were campgrounds in Death Valley, and much of Kings Canyon and Sequoia.

At each park, officials said health and safety concerns prompted the closures.

What’s the matter with people?

Sure, the government shutdown is a nuisance — especially for the 800,000 public employees who have been furloughed or ordered to work without pay. The shutdown also is a failure of leadership, most notably by President Donald Trump, who precipitated it with his demands for a border wall that wasn’t funded while his Republican party held majorities in both houses of Congress.

But politics, no matter how messy, is no excuse for befouling a park or any other public space.

Anyone who visits parks or beaches — or even takes a walk in town — knows that litter and vandalism are a constant problem. But it’s especially insidious during the shutdown because of the potential long-term effects on wildlife and sensitive habitats.

At Joshua Tree, volunteer cleanup crews reported finding empty champagne bottles on New Year’s Day. During three weeks of cleanup efforts, they filled bag after with trash, even a discarded prom dress, left behind by park visitors. Citizens are pitching in at other parks too, including Point Reyes National Seashore in Marin County, where a local hauling company is filling trucks with the trash left behind by visitors.

Democratic Reps. Jared Huffman and Jackie Speier led a weekend cleanup in the Golden Gate National Recreation Area. They planned to deposit some of the trash at the White House on Tuesday as a message to the president.

We’d like to send a message, too, echoing a letter to the editor in today’s paper from Micheline Justman of Santa Rosa. She recounts childhood visits to parks around the country, concluding with a question: “Doesn’t anyone’s mother say anymore, ‘Pick up your trash, and put it in the car. Leave nothing behind but your footprints’?”

You can send a letter to the editor at letters@pressdemocrat.com