Illinois Counties
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Illinois Counties

There are one hundred and two counties in Illinois. St. Clair County was the first county established in what is today Illinois. Most counties in Illinois were named after early American leaders, especially of the American Revolutionary War, as well as soldiers from the Battle of Tippecanoe and the War of 1812.

Monroe County, Illinois

Monroe County Education, Geography, and HistoryMonroe County, Illinois Courthouse

Monroe County is a county located in the state of Illinois. According to the 2010 census, it had a population of 32,957. Monroe County was created on January 6, 1816. The county seat and largest city is Waterloo. The county is named for James Monroe (1758-1831), seventh United States Secretary of State, eighth United States Secretary of War, Governor of Virginia, and fifth President of the United States.

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

Etymology - Origin of Monroe County Name

The county is named for President James Monroe, revolutionary soldier, diplomat; served two cabinet posts under President James Madison; known as co-negotiator of the Louisiana Purchase and author of the Monroe Doctrine.


County QuickFacts: CensusBureau Quick Facts

Monroe County History

Monroe County was created on January 6, 1816 (Laws, 1815/16, p. 25) and was formed from Randolph and St. Clair Counties. Present area, or parts of it, formerly included in: St. Clair County (1790-1816) and Randolph County (1795-1816).

The County was named for James Monroe, statesman and fifth president of the United States. He held numerous state and national offices in nearly 50 years of public service, and was a popular Democratic-Republican president (1817-1825). The County Seat is Waterloo . Prior County Seats was Harrisonville (1816-1825) and Waterloo (1825-Present).

Geography: Land and Water

As reported by the Census Bureau, the county has a total area of 398 square miles (1,030 km2), of which, 388 square miles (1,006 km2) of it is land and 9 square miles (24 km2) of it (2.37%) is water.

Monroe county is located in south Illinois.  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. Part of Kaskaskia River State Fish & Wildlife Area is in this county.

Neighboring Counties

Bordering counties are as follows:

  • Northeast: St. Clair County
  • Southeast: Randolph County
  • South: Ste. Genevieve County, Mo.
  • West: Jefferson County, Mo.
  • Northwest: St. Louis County, Mo.


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