Recently I was ask if any counties in the United States had ever been named after a black man. I said no, but perhaps I was technically incorrect.

Seattle, Washington, is located in King County.

From Wikipedia:

On February 24, 1986, the King County Council passed Motion 6461 renaming King County to commemorate the Rev. Dr. Martin Luther King, Jr. (1929-1968), the civil rights leader, rather than William Rufus de Vane King (1786-1853), the vice-president-elect for whom the county was named in 1852. The stated reason for the change was the revelation that "William Rufus DeVane King was a slaveowner and a "gentle slave monger" according to John Quincy Adams."[12]