Sullivan County, Tennessee

Sullivan County
Sullivan County Courthouse in Blountville
Location within the U.S. state of Tennessee
Tennessee's location within the U.S.
Coordinates: 36°31′N 82°18′W / 36.51°N 82.3°W / 36.51; -82.3
Country United States
State Tennessee
Founded1779
Named afterGeneral John Sullivan
SeatBlountville
Largest cityKingsport
Government
  County MayorRichard Venable (R)
Area
  Total
430 sq mi (1,100 km2)
  Land413 sq mi (1,070 km2)
  Water16 sq mi (40 km2)  3.8%
Population
 (2020)
  Total
158,163
  Estimate 
(2023)
162,135
  Density370/sq mi (140/km2)
Time zoneUTC−5 (Eastern)
  Summer (DST)UTC−4 (EDT)
Congressional district1st
Websitesullivancountytn.gov

Sullivan County is a county located in the U.S. state of Tennessee on its northeast border. As of the 2020 census, the population was 158,163. Its county seat is Blountville. Sullivan County is part of the KingsportBristol TN-VA Metropolitan Statistical Area, which is a component of the KingsportJohnson CityBristol, TN-VA Combined Statistical Area, commonly known as the "Tri-Cities" region. Sullivan is Tennessee's second-oldest county; it was established in 1779 when the area was still part of North Carolina. From 1784 to 1788, it was part of the extra-legal State of Franklin.