“As a general rule,” it was written in the 1920s, “Negroes have not been and are not thought of in America when you talk in general terms of Americans unless they are specifically pointed out.” This “general forgetfulness” therefore made it “necessary for those interested in fair play to all citizens” to propose a “beautiful building” to “depict the negro’s contribution to America in military service, in art, literature, invention, science, industry etc.”

The text was part of a century-long campaign, started by black civil war veterans in 1915, that will reach its fulfilment on Saturday, when Barack Obama formally opens the National Museum of African American History and Culture in Washington DC. It describes with some precision what has finally been achieved. It also suggests what the museum’s director, Lonnie Bunch, says over and over: that the museum should give “a fuller understanding of what it means to be American” seen through the “particular lens” of black experiences and contributions, not a place that is just about and for an anthropologically defined category known as African Americans.

The moment, of course, is charged. A short walk away another building has opened in the heart of the federal administrative district: the chandelier-bedecked Trump International hotel, a possible encampment on the way to the White House for the man keen on the plainly racist fantasy that Obama was not really American-born, and who as a young property tycoon was accused of denying homes to black applicants. Trump’s combinations of obfuscation, cunning, bluster and force follow a pattern seen across the centuries in the museum’s accounts of the ways in which black freedom and advancement were blocked.