Last month the National Archives found itself in the middle of a firestorm after it put a doctored photograph of the Women’s March on Washington on display. Even if the photo was not part of the National Archives’ own collection, the exhibit distorted history, and David S. Ferriero, the archivist of the United States, soon apologized.

This was only the latest example — and hardly the most important — of a great and growing threat to our nation’s capacity to protect and learn from history. The press and the public have focused on the immediate, obvious problems, like this president’s exaggerated claims of executive privilege and national security to conceal information. But less appreciated is the fact that vital information is actually being deleted or destroyed, so that no one — neither the press and government watchdogs today, nor historians tomorrow — will have a chance to see it.

President Trump has long made it a practice to tear up his papers and throw them away. It is a clear violation of the Presidential Records Act, which is supposed to prevent another Watergate-style cover-up. When the National Archives sent staff members to tape these records together, the White House fired them.

In 2017, a normally routine document released by the archives, a records retention schedule, revealed that archivists had agreed that officials from Immigration and Customs Enforcement could delete or destroy documents detailing the sexual abuse and death of undocumented immigrants. Tens of thousands of people posted critical comments, and dozens of senators and representatives objected. The National Archives made some changes to the plan, but last month it announced that ICE could go ahead and start destroying records from Mr. Trump’s first year, including detainees’ complaints about civil rights violations and shoddy medical care.