Sebastian County, Arkansas

Sebastian County, Arkansas
Arkansas River
Sebastian County Courthouse (Greenwood)
U.S. Marshals Museum
Location within the U.S. state of Arkansas
Coordinates: 35°35′39″N 94°15′29″W / 35.5942°N 94.2581°W / 35.5942; -94.2581
Country United States
State Arkansas
FoundedJanuary 6, 1851
Named afterWilliam K. Sebastian
SeatFort Smith (northern district);
Greenwood (southern district)
Largest cityFort Smith
Area
 • Total
546 sq mi (1,410 km2)
 • Land532 sq mi (1,380 km2)
 • Water14 sq mi (36 km2)  2.6%
Population
 (2020)
 • Total
127,799
 • Estimate 
(2024)
130,035
 • Density240/sq mi (92.8/km2)
Time zoneUTC−6 (Central)
 • Summer (DST)UTC−5 (CDT)
Congressional districts3rd, 4th
Websitewww.sebastiancountyar.gov

Sebastian County is a county located in the U.S. state of Arkansas. As of the 2020 census, the population was 127,799, making it the fourth-most populous county in Arkansas. The county has two county seats, Greenwood and Fort Smith.

Sebastian County is part of the Fort Smith metropolitan area.