2019-6-27 · Gallatin is a city in and the county seat of Sumner County, Tennessee.[4] The population was 30,678 at the 2010 census and 32,307 in 2013.[2] Named for U.S. Secretary of the Treasury Albert Gallatin, the city was established on the Cumberland River and made the county seat of Sumner County in 1802. It is located about 30.6 miles northeast of ...