What is the importance of the Ku Klux Klan as noted in the nonfiction book, The Warmth of Other Suns?

The Ku Klux Klan was an organization of white southerners who took vigilante action against the civil rights of black citizens. The violent behavior and hatred displayed by the Klan terrorized black citizens. The Klan was known to lynch blacks, burn crosses in front of their homes and burn down their property. The Klansmen, as they were known, wore white robes and white pointed head coverings that came down over their faces, with two eye holes to look out of. For decades, Southern law enforcement turned its head to the activities of the Klan.