Democrats who advanced a bill in June to remove statues of white supremacists from the U.S. Capitol ignored a central fact about those figures: All of them had been icons of their party, from Andrew Jackson’s adamantly pro-slavery vice president, John C. Calhoun, to North Carolina Gov. Charles B. Aycock, an architect of the white-supremacist campaign of 1898 that ushered in the era of Jim Crow.