From NKAA, Notable Kentucky African Americans Database (main entry)

Born in Virginia, Ansel Williamson was enslaved to T. G. Goldsby of Alabama and later bought by R. A. Alexander. Williamson was a horse trainer who conditioned many winners, including Aristides, winner of the first Kentucky Derby, ridden by Oliver Lewis. Williamson was the first African American trainer inducted into the National Museum of Racing and Hall of Fame in 1998. Williamson is listed in the 1880 U. S. Federal Census as having been born around 1810, though it has been published that he was born in 1806. He was in Kentucky for a number of years and worked at many stables. His career can be traced in newspaper articles such as "The Turf" and "Turf Notes." Ansel Williamson died in Lexington, KY, on June 18, 1881. The announcement of his death included a brief biography of his life in some newspapers.

For more see Black winning jockeys in the Kentucky Derby, by J. R. and M. R. Saunders; "The Turf," The Courier-Journal, 09/01/1870, p.3; "Ansel Williamson is dead!," The Tri-Weekly Yeoman, 06/23/1881, p.3; "Turf Notes," The Daily American (Tennessee), 05/25/1881, p.4; see Ansel Williamson at the National Museum of Racing and Hall of Fame website.