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.

Burkle and his descendants had good reason to avoid written records and to keep their activities secret. Memphis, on the eve of the Civil War, was one of the biggest slave markets in the South. After the war the city was an epicenter for Ku Klux Klan terror that included lynching, the nighttime burning of black churches and schools and the killing of black leaders and their white supporters, atrocities that continued into the 20th century. Martin Luther King Jr. was assassinated in Memphis in 1968. If word had gotten out that Burkle used his home to help slaves escape, the structure would almost certainly have been burned and Burkle or his descendants, at the very least, driven out of the city. The story of Burkle's aid to slaves fleeing bondage became public knowledge only a couple of decades ago.