Gatesville is a city in and the county seat of Coryell County, Texas, United States. Its population was 16,135 at the 2020 census. The city has fiv…Gatesville is a city in and the county seat of Coryell County, Texas, United States. Its population was 16,135 at the 2020 census. The city has five of the nine prisons and state jails for women operated by the Texas Department of Criminal Justice. One of the facilities, the Patrick O'Daniel Unit, has the state's death row for women.