Grayson is a home rule-class city in and the county seat of Carter County, Kentucky, United States, in the state's northeastern region. The population was 4,217 at the 2010 census. Along with Carter County, the city is closely associated with the nearby Huntington-Ashland, WV-KY-OH Metropolitan Statistical Area being just 9 miles west of the M.S.A's western boundary. The city has grown in size substantially since the opening of Interstate 64 in 1975 through Carter County