According to an interesting article by Jesse Washington of the Associated Press entitled “Washington Named the ‘Blackest Name’ in America,”
Based on the 2000 U. S. census, Washington is the most prominent surname among African Americans. 90% of 163,036 individuals with the Washington surname are African Americans, a far greater percentage than any other name.
The descendants of African Americans once enslaved on Wessyngton Plantation are part of this group. Before and after Emancipation, they chose to use the Washington surname—the surname of the slaveholding Washington family (were distant cousins of the president).
At the onset of the Civil War there were nearly 300 African Americans on Wessyngton Plantation. In 1870, 212 former slaves and their descendants from Wessyngton in Robertson County carried the Washington surname. This was nearly 5% of the total number of African Americans in the county.
In the years following the Civil War hundreds of Washingtons from Robertson County migrated out of the area. Today there are still African Americans in the area who carry the Washington surname (although far fewer than decades earlier), and some African American Washingtons throughout the country are descended from the Wessyngton Washingtons.