Whitesboro is a city in Grayson County, Texas, United States. The population was 4,074 at the 2020 census. Whitesboro is named for it…Whitesboro is a city in Grayson County, Texas, United States. The population was 4,074 at the 2020 census. Whitesboro is named for its founder, Ambrose B. White. It is part of the Sherman-Denison metropolitan area.