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.

McHenry County, Illinois

McHenry County Education, Geography, and HistoryMcHenry County, Illinois Courthouse

McHenry County is a county located in the state of Illinois. According to the 2010 census, it had a population of 308,760, making it the sixth-most populous county in Illinois. McHenry County was created on January 16, 1836. The county seat is Woodstock. The county is named for Major William McHenry (1771-1835), officer in during several campaigns against Native Americans and member of the Illinois legislature.

McHenry County is one of the five collar counties of the Chicago-Naperville-Elgin, IL-IN-WI Metropolitan Statistical Area.

Etymology - Origin of McHenry County Name

The county is named for General William McHenry, who fought in the War of 1812 and the Black Hawk War. General McHenry served in several early General Assemblies.


County QuickFacts: CensusBureau Quick Facts

McHenry County History

McHenry County was created on January 16, 1836 (Laws, 1836, p. 273) and was formed from Cook County and unorganized (La Salle County). Present area, or parts of it, formerly included in: Cook County (1831-1836), LaSalle County (1831-1836), Putnam County (1825-1831), Fulton County (1823-1825), Pike County (1821-1823), Clark County (1819-1821), Crawford County (1816-1819), Edwards County (1815-1816), Madison County (1812-1815), St. Clair County (1801-1812) and Knox, Northwest Territory (1795-1801).

The County was named for William McHenry, a pioneer of White County, soldier of the War of 1812 and the Black Hawk War, Representative in the first, fourth, fifth and ninth General Assemblies, and Senator in the sixth General Assembly. The County Seat is Woodstock . Prior County Seats was McHenry (1837-1843) and Woodstock- Named Centreville until 1844 (1843-Present).

 Long known as a center of agriculture and recreation, McHenry county has more recently experienced rapid rates of suburbanization and urbanization, but remains primarily agricultural and rural.

Geography: Land and Water

As reported by the Census Bureau, the county has a total area of 611 square miles (1,583 km2), of which, 604 square miles (1,563 km2) of it is land and 8 square miles (20 km2) of it (1.25%) is water.

McHenry county is located in north Illinois. Chain O'Lakes State Park and Moraine Hills State Park are located in this county.

Neighboring Counties

Bordering counties are as follows:

  • North: Walworth County, Wis.
  • Northeast: Kenosha County, Wis.
  • East: Lake County
  • Southeast: Cook County
  • South: Kane County
  • Southwest: DeKalb County
  • West: Boone County


McHenry County College, a rapidly growing community college established in 1967, serves the majority of county residents. The college includes 2,000 full-time students and 5,800 part-time students. The main campus is located on the northwest side of Crystal Lake, along US Route 14. Secondary facilities exist in Crystal Lake and McHenry.

McHenry County also includes dozens of school districts. There are also several high schools in the county. The largest high schools are McHenry High School East and West, Johnsburg High School, Woodstock High School, Woodstock North High School, Prairie Ridge High School, Crystal Lake Central High School, Crystal Lake South High School, Cary-Grove High School, Harry D. Jacobs High School, and Huntley High School, all of which are part of the Fox Valley Conference. Harvard High School, Richmond-Burton Community High School, and Marengo Community High School are part of the Big Northern Conference. Alden-Hebron High School, Faith Lutheran High School, and Marian Central Catholic High School are also found in the county.

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