Jefferson County, Iowa

Jefferson County
Courthouse in Fairfield is on the NRHP
Location within the U.S. state of Iowa
Iowa's location within the U.S.
Coordinates: 41°01′53″N 91°56′41″W / 41.031388888889°N 91.944722222222°W / 41.031388888889; -91.944722222222
Country United States
State Iowa
FoundedJanuary 21, 1839
Named afterThomas Jefferson
SeatFairfield
Largest cityFairfield
Area
  Total
437 sq mi (1,130 km2)
  Land436 sq mi (1,130 km2)
  Water1.4 sq mi (4 km2)  0.3%
Population
 (2020)
  Total
15,663
  Estimate 
(2023)
15,440
  Density36/sq mi (14/km2)
Time zoneUTC−6 (Central)
  Summer (DST)UTC−5 (CDT)
Congressional district1st
Websitehttps://jeffersoncounty.iowa.gov/

Jefferson County is a county located in the U.S. state of Iowa. As of the 2020 United States census, the population was 15,663. The county seat is Fairfield. The county was formed in January 1839, and was named for U.S. President Thomas Jefferson. Jefferson County comprises the Fairfield, IA Micropolitan Statistical Area.