The sociologist James Loewen documented the practice in his 2005 book Sundown Towns. He found that many towns drove out Black residents in waves of violence between 1890 and 1940 and then kept them out for decades. Some posted signs at the town limits. Others relied on police harassment, refusals to sell or rent homes, and the threat of mob violence. Some towns and suburbs also excluded Chinese, Jewish, Mexican American or Native people.
In 1912, white mobs in Forsyth County, Georgia, forced out more than 1,000 Black residents, and the county stayed nearly all white for decades. Black travelers relied on The Green Book to avoid sundown towns while driving.
The Fair Housing Act of 1968 made housing exclusion illegal, but the patterns lasted. Many former sundown towns remain overwhelmingly white, and some Black travelers still report feeling unsafe passing through them.