To some people, the name of Angola, the Louisiana State Penitentiary, brings to mind the country’s oldest prison rodeo, which draws thousands of tourists while raising money for charity. Others think of it as a repository for fearsome criminals — murderers, rapists and kidnappers — who have earned their average sentence of 93 years. Many remember it as having once been one of the most brutal and corrupt institutions in the post-Civil War South, the nearest kin to slavery that could legally exist.

All of these associations and more will compete when an old guard tower and a cell from the prison are installed in the forthcoming National African American Museum for History and Culture in Washington, a place with the complex mission of presenting an official narrative of black life in America....