Montgomery County, Illinois

Montgomery County, Illinois
Location within the U.S. state of Illinois
Coordinates: 39°14′N 89°29′W / 39.23°N 89.48°W / 39.23; -89.48
Country United States
State Illinois
Founded1821
Named afterRichard Montgomery
SeatHillsboro
Largest cityLitchfield
Area
 • Total
710 sq mi (1,800 km2)
 • Land704 sq mi (1,820 km2)
 • Water6.0 sq mi (16 km2)  0.8%
Population
 (2020)
 • Total
28,288
 • Estimate 
(2024)
27,615
 • Density40.2/sq mi (15.5/km2)
Time zoneUTC−6 (Central)
 • Summer (DST)UTC−5 (CDT)
Congressional district15th
Websitemontgomerycountyil.gov

Montgomery County is a county located in the U.S. state of Illinois. According to the 2020 United States census, it had a population of 28,288. Its county seat is Hillsboro.