Sweetwater is a municipality in and the seat of Nolan County, Texas, United States.It is 236 miles southeast of Amarillo and 181 miles west of Fort Worth. The population was 10,906 at the 2010 census. Sweetwater received a U.S. post office in 1879. The Texas and Pacific Railway started service in 1881, with the first train arriving on March 12 of that year, beginning Sweetwater’s long history as a railroad town. To encourage the railroads, Sweetwater increased its water supply by building a small town lake in 1898, and three larger lakes thereafter. Construction began on the Kansas City, Mexico and Orient Railway in 1903. Sweetwater became a railroad town, with businesses and homes built along the rail line. Rail passenger service was discontinued in 1969.