On a sunny Saturday in June, thousands gathered on the National Mall in Washington, D.C., to sing “The Star-Spangled Banner.” This year marks the two-hundredth anniversary of Francis Scott Key’s composition, officially adopted as the national anthem in 1931 following news that leftist members of the Erie, Pennsylvania, city council were opening meetings with a rousing chorus of “The Internationale.” As the melody rang out over the grass and along Constitution Avenue, it echoed off neighboring memorials and galleries, including the partly built National Museum of African American History and Culture a block and a half down the street.
Although…