McHenry County, Illinois

McHenry County: County in Illinois, United States


McHenry County is a county located in the U.S. state of Illinois. As of the 2010 census, the population was 308,760 and a population density of 198 people per km². After 10 years in 2020 county had an estimated population of 305,888 inhabitants. Its county seat is Woodstock. The county was created 188 years ago in 1835.

McHenry County locator map
Location of McHenry County on Illinois map.

Quick Facts about McHenry County

Population : 305,888 (2020)
Country : United States of America
State : Illinois (United States)
Different from : McHenry County
Area : 1563 km2
Water as percent of area : 1.3%
Land as percent of area : 98.7%
Named for : William McHenry
Altitude : 886 feet / 270 meters
Capital : Woodstock
Establishment : January 01, 1836
Time Zone : America/Chicago
Local time : 10:12:16 (2nd March 2024)
Density : 196 Pop. per km² as of 2020
Population growth : -0.94% (2010-2020)
WoodstockILCourtHJail image
WoodstockILCourtHJail image


McHenry County is located at 42°19'28"N 88°27'9"W (42.3243900, -88.4524500). It has 5 neighbors: Boone County, Cook County, DeKalb County, Kenosha County and Walworth County.

McHenry County map

The largest city of McHenry County is Crystal Lake with a population of 39,642. Other cities include, McHenry population 27,100, Harvard population 8,979, Marengo population 7,377 and Lakemoor population 5,912. See all McHenry County cities & populated places.

McHenry County Populated Places (more)

Cities, towns, neighborhoods & other populated places in McHenry County.

City Name Population Title
Crystal Lake 39,642 City located in McHenry County, Illinois, USA
Algonquin 30,730 Village in Illinois
Lake in the Hills 28,345 Village in Illinois
Huntley 27,256 Village in McHenry and Kane counties, Illinois, United States
McHenry 27,100 City in Illinois
Cary 17,929 Village in Illinois, United States
Harvard 8,979 Private research university in Cambridge, Massachusetts, United States
Chemung 8,702 Township in McHenry County, Illinois
Marengo 7,377 City in McHenry County, Illinois, United States
Johnsburg 6,310 Village in United States of America
Lakemoor 5,912 City in Illinois, United States of America
Spring Grove 5,679 City in Houston County, Minnesota, United States
Fox River Grove 4,518 City in United States of America
Lawrence 4,380 Township in Lawrence County, Illinois
Wonder Lake 3,837 Human settlement in Illinois, United States of America
Pistakee Highlands 3,454 Census designated place

McHenry County has 5 neighbours.


According to census records, the population of McHenry County decreased by 0.94% in 10 years.

Year Population % Change Method
2010 308,760 - census
2011 308,504 -0.08% estimation process
2012 308,230 -0.09% estimation process
2013 307,605 -0.2% estimation process
2014 307,404 -0.07% estimation process
2015 307,572 0.05% estimation process
2016 307,159 -0.13% estimation process
2017 307,815 0.21% estimation process
2018 308,251 0.14% estimation process
2019 307,774 -0.15% estimation process
2020 305,888 -0.62% estimation process

Comitatul McHenry, Comte de McHenry, Comté de McHenry, Condado de McHenry, Condado han McHenry, Contea di McHenry, Hrabstwo McHenry, Mak-Genri, Makgenri, Makhenri srjan, Makkhenri, McHenry, McHenry Comitatus, McHenry Kun, McHenry Kūn, McHenry konderria, McHenry maakond, McHenry megye, Okrug Makkhenri, Quan McHenry, Quận McHenry, mai ke heng li xian, makuhenri jun, mqatʿt mkhnry, myakahenari ka'unti, Мак-Генри, Макгенрі, Макхенри, Округ Макхенри, Մակհենրի շրջան, مقاطعة مكهنري, مکہنری کاؤنٹی, مکہینری کاؤنٹی، الینوائے, ম্যাকহেনরি কাউন্টি, マクヘンリー郡, 麥克亨利縣

People born in McHenry County (3)

People born in McHenry County, including politician T. V. Eddy, politician M. F. Hatch, politician Frank H. Richards, .


Other places with the same name (2)

Illinois Other Counties (more counties)

County Name Population Title
Cook County 5,108,284 County in Illinois, United States
Chicago 2,677,643 The third most populous city in the United States and the center of the Chicago metropolitan area.
DuPage County 917,481 County in Illinois, United States
Lake County 693,593 County in Oregon, United States
Will County 688,726 County in Illinois, United States
Kane County 531,010 County in southern Utah, United States
Winnebago County 281,295 County in Illinois, United States
Madison County 262,635 County in Montana, United States
Saint Clair County 258,046 The County of St.
Champaign County 209,192 County in Illinois, United States
Aurora 196,383 The second most populous city in Illinois.
Sangamon County 193,882 County in Illinois, United States
Peoria County 177,652 County in Illinois, United States of America
McLean County 171,256 County in North Dakota, United States
Naperville 147,986 The second most populous city in Illinois.
Rockford 144,835 The second most populous city in Illinois.