I recently watched Welcome to Leith, a 2015 documentary about white supremacist Craig Cobb’s attempt to take over a tiny village by persuading others of his ilk to move there. The native villagers resist him. The film’s an interesting time capsule from just seven years ago, before “Nazi” became a brush to paint all Trump supporters.

Leith, North Dakota had one African-American among the two dozen residents, and was…