New York, both the city and the state, is named after the house of York and particularly for James Stuart, then Duke of York, one of the most successful slavers in colonial American history. President Donald Trump wondered aloud during a raucous press conference Tuesday whether the impulse to tear down memorials to leaders of the Confederacy like Gen. Robert E. Lee would slip into calls to remove monuments to America’s founders, like Thomas Jefferson and George Washington, both of whom owned slaves. The memory of slavery is enshrined in the name New York as well as the name of...