Map of Marion County, Illinois

Marion County is a county located in the U.S. state of Illinois. According to the 2010 census, it had a population of 39,437. Its county seat is Salem.

Marion County comprises the Centralia, IL Micropolitan Statistical Area, which is included in the St. Louis–St. Charles–Farmington, MO-IL Combined Statistical Area.

Marion County overview:
Name:	Marion County
FIPS code:	17-121
State:	Illinois
Founded:	1823
Named for:	Francis Marion
Seat:	Salem
Largest city:	Centralia
Total Area:	576 sq mi (1,490 km²)
Land Area:	572 sq mi (1,480 km²)
Total Population:	39,437
Population Density:	68/sq mi (26/km²)
Time zone:	UTC−6 (Central)
Summer Time Zone (DST):	UTC−5 (CDT)

Marion County location map. Where is Marion County?

Marion County location on the U.S. Map. Where is Marion County. — Location of Marion County in the the United States.

Marion County location on the Illinois map. Where is Marion County. — Location of Marion County in Illinois.

History

Marion County was organized on 24 January 1823 from portions of Jefferson and Fayette counties. It was named in honor of Revolutionary War Gen. Francis Marion, the “Swamp Fox”.

Marion County at the time of its creation in 1823

Marion County Road Map

Marion CountyStreet Map. — Street map of Marion County, Illinois. Source: OpenStreetMap (OSM)

Marion CountyMap — Marion Countypolitical map.

Geography

According to the U.S. Census Bureau, the county has a total area of 576 square miles (1,490 km), of which 572 square miles (1,480 km) is land and 3.7 square miles (9.6 km) (0.6%) is water.

The southwest corner of Marion County is the intersection of the Baseline with the Third Principal Meridian, the point of origin for the third survey of the Northwest Territory under the Land Ordinance of 1785. The origin is marked with a boulder south of Centralia just off U.S. 51.

Climate and weather

In recent years, average temperatures in the county seat of Salem have ranged from a low of 18 °F (−8 °C) in January to a high of 88 °F (31 °C) in July, although a record low of −23 °F (−31 °C) was recorded in January 1994 and a record high of 105 °F (41 °C) was recorded in August 1983. Average monthly precipitation ranged from 2.46 inches (62 mm) in January to 4.37 inches (111 mm) in May.