Mason County, Illinois

Mason County
Mason County Courthouse, Havana
Location within the U.S. state of Illinois
Illinois's location within the U.S.
Coordinates: 40°14′N 89°55′W / 40.24°N 89.91°W / 40.24; -89.91
Country United States
State Illinois
Founded1841
Named afterGeorge Mason
SeatHavana
Largest cityHavana
Area
  Total
563 sq mi (1,460 km2)
  Land539 sq mi (1,400 km2)
  Water24 sq mi (60 km2)  4.3%
Population
 (2020)
  Total
13,086
  Estimate 
(2021)
12,881
  Density23/sq mi (9.0/km2)
Time zoneUTC−6 (Central)
  Summer (DST)UTC−5 (CDT)
Congressional district15th
Websitewww.masoncountyil.gov

Mason County is a county in the U.S. state of Illinois. According to the 2020 census, it had a population of 13,086. Its county seat is Havana. The county is named in honor of George Mason, a member of the Virginia legislature who campaigned for the adoption of the United States Bill of Rights.