Monroe County
Monroe County Courthouse in Waterloo
Monroe County Courthouse in Waterloo
Map of Illinois highlighting Monroe County
Location within the U.S. state of Illinois
Map of the United States highlighting Illinois
Illinois's location within the U.S.
Coordinates: 38°17′N 90°11′W / 38.28°N 90.18°W / 38.28; -90.18
Country United States
State Illinois
Named forJames Monroe
Largest cityWaterloo
 • Total398 sq mi (1,030 km2)
 • Land385 sq mi (1,000 km2)
 • Water13 sq mi (30 km2)  3.3%
 • Total34,962
 • Density88/sq mi (34/km2)
Time zoneUTC−6 (Central)
 • Summer (DST)UTC−5 (CDT)
Congressional district12th

Monroe County is a county located in the U.S. state of Illinois. According to the 2020 census, it had a population of 34,962.[1] Its county seat and largest city is Waterloo.[2]

Monroe County is included in the St. Louis, MO-IL Metropolitan Statistical Area. It is located in the southern portion of Illinois known historically as "Little Egypt".


Indigenous peoples lived along the Mississippi River and related waterways for thousands of years before European contact. French Jesuit priests in the Illinois Country encountered the Kaskaskia and Cahokia, bands of the Illiniwek confederacy.

The first European settlement in this area was St. Philippe, founded in 1723 by Philippe François Renault, a French courtier, on his concession about three miles north of Fort de Chartres along the Mississippi River. This early agricultural community quickly produced a surplus, and grains were sold to the lower Louisiana colony for years. They were integral to that community's survival, as its climate did not allow cultivation of such staple grains.

Monroe County was formed in 1816 out of Randolph and St. Clair counties, as the 8th county created from the then Illinois Territory.

Beginning on the Mississippi River where the base line, which is about three-fourths of a mile below Judge Briggs's present residence, strikes the said river; thence with the base line until it strikes the first township line therefrom; thence southeast to the southeast corner of township two south, range nine west; thence south to the southeast corner of township four north, range nine west; thence southwestwardly to the Mississippi, so as to include Alexander McNabb's farm, and thence up the Mississippi to the beginning shall constitute a separate county, to be called MONROE.
Illinois Territorial Laws 1815-16, p. 25[3]

It was named in honor of James Monroe,[4] who had just served as United States Secretary of War and who was elected President later that same year. Its first county seat was Harrisonville, named for William Henry Harrison, former governor of the Northwest Territory and future President. Harrison invested in several tracts of land in the American Bottoms above Harrisonville, mostly in the present precinct of Moredock, ownership of which he retained until his death.[5]

Waterloo was designated as the mantle of county seat in 1825. The sites of the colonial towns of St. Philippe and Harrisonville were submerged by the Mississippi River, in flooding caused by deforestation of river banks during the steamboat years. Crews cut so many trees that banks destabilized and collapsed in the current, making the river wider and more shallow from St. Louis to the confluence with the Ohio River. This change caused more severe flooding, as well as lateral channel changes, such as the one that cut off the village of Kaskaskia from the Illinois mainland.[6]

An unincorporated community of Harrisonville was re-established east of the original site. The bounds of Monroe County in 1816 did not include Precincts 1 and 6 (village of Hecker and Prairie du Long), Precinct 1 and most of 6 was added in 1825 from St. Clair County.[7] The strip of Precinct 6 from the survey township line east to the Kaskaskia was added, once again from St. Clair, two years later in 1827.[8] Some minor adjustments and clarifications of the boundaries have taken place, but the borders have remained essentially static since 1827.


According to the U.S. Census Bureau, the county has a total area of 398 square miles (1,030 km2), of which 385 square miles (1,000 km2) is land and 13 square miles (34 km2) (3.3%) is water.[9]

The western part of the county on the Mississippi River is part of the American Bottom floodplain, while the eastern portion of the county is relatively flat and was originally prairie. The transition zone between has high bluffs of limestone and dolomite and has distinctive Karst topography with numerous sinkholes, caves, and springs.

Climate and weather

Waterloo, Illinois
Climate chart (explanation)
Average max. and min. temperatures in °F
Precipitation totals in inches
Source: The Weather Channel[10]

In recent years, average temperatures in the county seat of Waterloo have ranged from a low of 20 °F (−7 °C) in January to a high of 89 °F (32 °C) in July, although a record low of −18 °F (−28 °C) was recorded in December 1989 and a record high of 107 °F (42 °C) was recorded in August 1962. Average monthly precipitation ranged from 2.32 inches (59 mm) in January to 4.25 inches (108 mm) in July.[10]

Major highways

Adjacent counties


Historical population
Census Pop.
U.S. Decennial Census[11]
1790-1960[12] 1900-1990[13]
1990-2000[14] 2010-2013[1] 2020[15]

As of the 2010 United States Census, there were 32,957 people, 12,589 households, and 9,375 families residing in the county.[16] The population density was 85.6 inhabitants per square mile (33.1/km2). There were 13,392 housing units at an average density of 34.8 per square mile (13.4/km2).[9] The racial makeup of the county was 98.0% white, 0.4% Asian, 0.2% American Indian, 0.2% black or African American, 0.3% from other races, and 0.8% from two or more races. Those of Hispanic or Latino origin made up 1.4% of the population.[16] In terms of ancestry, 53.9% were German, 16.5% were Irish, 9.6% were English, and 6.2% were American.[17]

Of the 12,589 households, 34.7% had children under the age of 18 living with them, 62.9% were married couples living together, 7.9% had a female householder with no husband present, 25.5% were non-families, and 21.5% of all households were made up of individuals. The average household size was 2.59 and the average family size was 3.02. The median age was 41.0 years.[16]

The median income for a household in the county was $68,253 and the median income for a family was $80,832. Males had a median income of $55,988 versus $39,375 for females. The per capita income for the county was $31,091. About 3.5% of families and 4.5% of the population were below the poverty line, including 4.3% of those under age 18 and 2.4% of those age 65 or over.[18]



Provides access to the Interstate System, South Saint Louis County via the J.B. bridge as well as Downtown St. Louis and western St. Clair County
Provides access to the Interstate System, South Saint Louis County via the J.B. bridge as well as Downtown St. Louis and western St. Clair County
Main north-south corridor and the backbone of Monroe County
Briefly overlaps Illinois Route 159 in and just north of Hecker
Also called the Valmeyer highway or Hecker highway, west and east of Waterloo, respectively, it runs from the bluffs of the Mississippi to the Kaskaskia
The area's main link with central and eastern St. Clair County for those not near Hecker
Briefly overlaps Illinois Route 156 in and just north of Hecker
Significant eastern north-south corridor, provides alternate routes, and primary north-south link for Prairie Du Long and Hecker

County roads

runs along the bluffs from Palmer Rd. northwest of Columbia, through old Valmeyer and Chalfin Bridge, past Fults to Prairie du Rocher in Randolph County
runs from Illinois Route 3 in Waterloo (as Lakeview Drive) through Wartburg and Maeystown to Bluff Rd. at Chalfin Bridge
historic route from Kaskaskia to St. Louis, leaves Illinois Route 3 south of Waterloo, passes through Burksville and St. Joe, descends into the Bottoms outside Renault, crosses Bluff Rd. and railroad tracks to Stringtown Rd.
Runs from Route 3 west, past New Hanover down the Fountain Gap to Bluff Rd. at Miles Rd. and B Rd.. Marks approximate future border between Columbia and Waterloo.
Northern terminus at Rt. 3/Main St. four-way in Columbia, south across Hanover Rd., and southern terminus at HH Rd. northwest of Waterloo and near Annbriar Golf Course.
Runs from Gilmore Lakes Rd., north of Floraville Rd., west across Route 3 in Waterloo (as Country Club Ln.) to Bluff Rd. east of Fountain
Runs from the Mississippi River levee opposite Crystal City, Missouri, west across Bluff Rd. up the bluffs at Monroe City, through Madonnaville, across Maeystown Rd., through Burksville and Burksville Station, across Route 3 to J Rd. south of Route 156
With a western terminus at Franklin St. in Maeystown, it travels east across Kaskaskia Rd., through Tipton, across Route 3, temporarily overlaps with J Rd. for about 0.5 miles east of Rt. 3 and west of Rt. 159, crosses Rt. 159 south of Hecker and north of Red Bud, ends with eastern terminus at Beck Rd. just west of the Kaskaskia River and near the Nike Missile Site.

Public Transportation

There is a regular MetroBus express bus, 502X Waterloo-Columbia, running from Waterloo, through Columbia, to the MetroLink station in East St. Louis.


J. B. Bridge during the flood of 1993
Bridges and ferries
Jefferson Barracks Bridge - crosses the Mississippi northwest of Columbia, carries Interstate 255
Bridges and ferries

The closest access to and bridges over the Kaskaskia are downriver at Baldwin in Randolph County and upriver at New Athens in St. Clair County. South of Monroe County, there is a ferry across the Mississippi in Randolph County, providing access to Ste. Genevieve, Missouri and Pere Marquette State Park, and a bridge at Chester.


While the railroad played a large part in the history and development of the county, the main line through the county, running along Illinois Route 3, has been abandoned and removed. However, Union Pacific tracks run through the Bottoms from the intermodal yard at Dupo in St. Clair County, running roughly parallel to Bluff Rd. which crosses them several times, through old Valmeyer and Fults on past Prairie du Rocher in Randolph County. The tracks are still in use, but carry only freight, and have no stops in Monroe County.


There is a small airfield in the Bottoms west of Columbia called Sackman Field.




Unincorporated Communities

Former Settlement


For census and election purposes, Monroe County is currently divided into 26 numbered precincts (1-27, for some reason there is no Precinct 14). However, for geographical, genealogical, and historic purposes the older, named precincts are of greater utility.

named for the ubiquitous limestone cliffs it sits atop and which run along its western bounds.
formerly Eagle Precinct from the original French name for their settlement, L'Aigle
honors William Henry Harrison who also gave his name to a settlement
so named for the Mitchegamie Indians who at one time inhabited the extreme southern part of the county
after John Moredock, territorial legislator, and Major commanding a battalion in the War of 1812
named after the settlement began by James Lemen, a confidante of Thomas Jefferson, in 1786
as with the settlement, its name recalls Hanover, Germany, hometown of the settlements founder
from hybrid French/English "Long Prairie", it was added in 1825, after the county's genesis, the strip along the river in 1827.
also a settlement, for Philip Francois Renault of the French Company of the Indies, an early exploiter of the area
formerly Fountain Precinct, from Fountain Creek which runs through it on its way to the bluffs and down to the river


Monroe County, along with neighboring Randolph County, is located within Regional Office of Education #45.[19]


This article needs additional citations for verification. Please help improve this article by adding citations to reliable sources. Unsourced material may be challenged and removed.Find sources: "Monroe County, Illinois" – news · newspapers · books · scholar · JSTOR (May 2022) (Learn how and when to remove this template message)

Monroe County was hostile to the “YankeeCivil War and voted solidly Democratic until Theodore Roosevelt carried the county in 1904. Since that time, however, the county has become predominately Republican, and the only Democrats to gain a majority since 1904 have been Catholic Al Smith in 1928, Franklin D. Roosevelt in 1932 and 1936, and Lyndon Johnson in 1964. Since 1968, Monroe County has been carried by the Republican Presidential nominee in every election except when Bill Clinton won a narrow plurality in 1992.

United States presidential election results for Monroe County, Illinois[20]
Year Republican Democratic Third party
No.  % No.  % No.  %
2020 14,142 66.69% 6,569 30.98% 495 2.33%
2016 12,629 65.25% 5,535 28.60% 1,190 6.15%
2012 10,888 62.24% 6,215 35.53% 391 2.24%
2008 9,881 54.50% 7,953 43.87% 295 1.63%
2004 9,468 57.84% 6,788 41.47% 114 0.70%
2000 7,632 55.32% 5,797 42.02% 367 2.66%
1996 5,350 46.38% 4,798 41.60% 1,387 12.02%
1992 4,807 38.33% 4,894 39.02% 2,841 22.65%
1988 6,275 57.83% 4,529 41.74% 47 0.43%
1984 6,936 67.89% 3,256 31.87% 25 0.24%
1980 6,315 63.63% 3,121 31.45% 488 4.92%
1976 5,602 57.66% 3,984 41.00% 130 1.34%
1972 6,479 68.44% 2,958 31.25% 29 0.31%
1968 5,086 55.48% 2,822 30.78% 1,259 13.73%
1964 3,936 46.08% 4,605 53.92% 0 0.00%
1960 4,731 58.17% 3,398 41.78% 4 0.05%
1956 4,715 64.03% 2,648 35.96% 1 0.01%
1952 4,528 65.07% 2,430 34.92% 1 0.01%
1948 3,403 62.65% 2,026 37.30% 3 0.06%
1944 4,032 66.00% 2,068 33.85% 9 0.15%
1940 4,754 62.54% 2,826 37.17% 22 0.29%
1936 3,226 47.09% 3,477 50.76% 147 2.15%
1932 2,186 34.93% 3,993 63.80% 80 1.28%
1928 2,721 48.03% 2,934 51.79% 10 0.18%
1924 2,390 48.35% 1,369 27.70% 1,184 23.95%
1920 2,955 70.11% 932 22.11% 328 7.78%
1916 2,825 56.91% 2,104 42.39% 35 0.71%
1912 1,433 45.42% 1,398 44.31% 324 10.27%
1908 1,733 52.95% 1,512 46.20% 28 0.86%
1904 1,622 52.32% 1,440 46.45% 38 1.23%
1900 1,535 46.40% 1,757 53.11% 16 0.48%
1896 1,446 46.18% 1,652 52.76% 33 1.05%
1892 1,153 40.05% 1,611 55.96% 115 3.99%

See also


  1. ^ a b "State & County QuickFacts". United States Census Bureau.
  2. ^ "Find a County". National Association of Counties. Retrieved June 7, 2011.
  3. ^ Counties of Illinois, p. 32-33. With Twenty-three Maps Showing the Original and the Present Boundary Lines of Each County of the State, Retrieved on January 22, 2008.
  4. ^ Gannett, Henry (1905). The Origin of Certain Place Names in the United States. U.S. Government Printing Office. p. 212.
  5. ^ Combined History of Randolph, Monroe and Perry Counties, Illinois, J. L. McDonough & Co., Philadelphia, 1883
  6. ^ F. Terry Norris, "Where Did the Villages Go? Steamboats, Deforestation, and Archaeological Loss in the Mississippi Valley", in Common Fields: An Environmental History of St. Louis, Andrew Hurley, ed., St. Louis, MO: Missouri Historical Society Press, 1997, pp. 73-89
  7. ^ "Counties of Illinois pg. 46-47". 1825 Retrieved on January 22, 2008.
  8. ^ "Counties of Illinois, pg. 49-50". 1827 Retrieved on January 22, 2008.
  9. ^ a b "Population, Housing Units, Area, and Density: 2010 - County". United States Census Bureau. Archived from the original on February 13, 2020. Retrieved July 12, 2015.
  10. ^ a b "Monthly Averages for Waterloo, Illinois". The Weather Channel. Retrieved January 27, 2011.
  11. ^ "U.S. Decennial Census". United States Census Bureau. Retrieved July 7, 2014.
  12. ^ "Historical Census Browser". University of Virginia Library. Retrieved July 7, 2014.
  13. ^ "Population of Counties by Decennial Census: 1900 to 1990". United States Census Bureau. Retrieved July 7, 2014.
  14. ^ "Census 2000 PHC-T-4. Ranking Tables for Counties: 1990 and 2000" (PDF). United States Census Bureau. Retrieved July 7, 2014.
  15. ^ "Explore Census Data".
  16. ^ a b c "DP-1 Profile of General Population and Housing Characteristics: 2010 Demographic Profile Data". United States Census Bureau. Archived from the original on February 13, 2020. Retrieved July 12, 2015.
  17. ^ "DP02 SELECTED SOCIAL CHARACTERISTICS IN THE UNITED STATES – 2006-2010 American Community Survey 5-Year Estimates". United States Census Bureau. Archived from the original on February 13, 2020. Retrieved July 12, 2015.
  18. ^ "DP03 SELECTED ECONOMIC CHARACTERISTICS – 2006-2010 American Community Survey 5-Year Estimates". United States Census Bureau. Archived from the original on February 13, 2020. Retrieved July 12, 2015.
  19. ^ "Directory July 1, 2020-June 30, 2021" (PDF). Illinois Association of Regional Superintendents of Schools. p. 6. Archived from the original (PDF) on December 4, 2020. Retrieved April 24, 2022.
  20. ^ Leip, David. "Dave Leip's Atlas of U.S. Presidential Elections". Retrieved March 19, 2018.

Coordinates: 38°17′N 90°11′W / 38.28°N 90.18°W / 38.28; -90.18