Gainesville is a city in and the county seat of Cooke County, Texas, United States. The population was 15,538 at the 2000 census. Founded in 1850, the city of Gainesville was established on a 40-acre tract of land donated by Mary E. Clark. City residents called their new community Liberty, which proved short-lived, as a Liberty, Texas already existed. It was suggested by one of the original settlers of Cooke County, Colonel William Fitzhugh, that the town be named after General Edmund Pendleton Gaines. Gaines, a United States General under whom Fitzhugh had served, had been sympathetic with the Texas Revolution.