Presidential libraries play a unique role in U.S. politics. They are part museum, part memorial, part repository. They look backward and forward, telling the story of an administration’s course while trying to teach its lessons to future generations.

That’s why their message to the United States this week is important. On Thursday, 13 presidential libraries and associated foundations dating back to Herbert Hoover issued a joint call for Americans to recommit to founding democratic values, including the rule of law, tolerance for other views, and commitment to peaceful transfers of power.

“As a diverse nation of people with different backgrounds and beliefs, democracy holds us together,” said the statement.

Americans have a strong interest in supporting democratic values around the world because free societies everywhere contribute to U.S. security and prosperity, said signers.

“But that interest is undermined when others see our own house in disarray,” the statement concluded.

The idea for the library alliance originated at the George W. Bush Presidential Center. Most living presidents have generally avoided commenting directly about the polarized state of U.S. politics. Polls show many Republicans back former President Donald Trump’s unsubstantiated claims that the 2020 election was stolen, while Mr. Trump excoriates the country’s legal system as he faces multiple criminal indictments.

The statement does not name any particular person or party. Libraries from the Obama Foundation back through the Roosevelt Institute signed, with the exception of the Eisenhower Foundation.

“I think there’s a great concern about the state of our democracy at this time,” Mark Updegrove, head of the LBJ Foundation, told The Associated Press. “We don’t have to go much farther than Jan. 6 to realize we are in a perilous state.”