To trace your African-American ancestors before 1870, standard genealogical techniques don't apply. Identifying slave ancestors, like these pictured outside their house in Fredericksburg, Va., circa 1862-1865, involves tracing the slaveholding families and locating their records.

In 1619, Dutch slave traders sold 20 African captives to the settlers of Jamestown, Va. For Americans with roots in Africa, this marked the beginning of your ancestors' arrival in America. By 1808, when the importation of slaves was constitutionally prohibited, the United States was home to some 1 million slaves.