On a windy afternoon a few days ago I went to a depressed section of North Memphis to visit an old clapboard house that was once owned by a German immigrant named Jacob Burkle. Oral history—and oral history is all anyone has in this case since no written documents survive—holds that Burkle used his house as a stop on the underground railroad for escaped slaves in the decade before the Civil War. The house is now a small museum called Slave Haven. It has artifacts such as leg irons, iron collars and broadsheets advertising the sale of men, women and children. In the gray floor of the porch there is a trapdoor that leads to a long crawl space and a jagged hole in a brick cellar wall where fugitives could have pushed themselves down into the basement. Escaped slaves were purportedly guided by Burkle at night down a tunnel or trench toward the nearby Mississippi River and turned over to sympathetic river traders who took them north to Cairo, Ill., and on to freedom in Canada.