Illinois

McHenry

310,229
2020 population
1840
first census record
19
census records

About McHenry

McHenry, Illinois, first appears in the United States federal census in 1840, when it recorded a population of 2,578. At the most recent census, in 2020, its population stood at 310,229.

The county's recorded population has risen across the decades to its highest level in 2020.

On the ground today, 2 documented military engagements have been recorded within the county, among them Skirmish at Buffalo Grove, Buffalo Grove Skirmish, and 29 places are listed on the National Register of Historic Places.

Population by decade

Census YearPopulationChart
2020310,229
2010308,760
2000260,077
1990183,241
1980147,897
1970111,555
196084,210
195050,656
194037,311
193035,079
192033,164
191032,509
190029,759
189026,114
188024,908
187023,762
186022,089
185014,978
18402,578
Source

Population data from the United States decennial census, U.S. Census Bureau (public domain).

Battles & engagements in McHenry

Military engagements that took place in McHenry, Illinois.

Skirmish at Buffalo Grove
1832
Buffalo Grove Skirmish
1832

Historic places in McHenry

National Register of Historic Places listings in McHenry, Illinois.

Covell, Lucein Boneparte, House
Richmond
Woodstock Opera House
Woodstock
Geister, Christian, House
Algonquin
Memorial Hall
Richmond
Hibbard, Charles H., House
Marengo
Palmer, Col. Gustavus A., House
Crystal Lake
Stickney, George, House
Woodstock
Old McHenry County Courthouse
Woodstock
Woodstock Square Historic District
Woodstock
Terwilliger House
Woodstock
Rogers, Orson, House
Marengo
Count's House
McHenry
Browse all Illinoishistoric sites ›

Other counties in Illinois

Explore census history and historic records for more Illinois counties.

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Everything a full report reveals about McHenry County, Illinois

This page charts the census history of McHenry County, Illinois. A full Aubrey report for an address here pulls together everything the historical record holds about the ground, from the earliest settlement to the twentieth century:

Overview
An interactive map of the location with historic sites, battles and Native heritage plotted, and its full story era by era.
The Land
The historic sites and place names around the location, and how this land was settled and used.
Geology
The bedrock beneath the site, its age and rock type, reaching back millions of years.
LiDAR Terrain
Laser-scanned terrain that reveals earthworks and old features hidden in the landscape.
Conflict & War
The battles, raids and skirmishes fought near here, across every era of American conflict.
The Civil War
The Civil War on this ground, 1861 to 1865: who held it, and the battles, camps and regiments nearby.
The Soldiers
The men who marched from here in the Civil War, named and traced where the record allows.
Native Heritage
The Native nations who held this land, mapped across time from before European contact to today.
Settlement
Who claimed and held this ground, from Indigenous homelands through the colonial powers to the United States.
The Community
How the town grew, who came, and what kind of place it became, traced through the census record.
Rivers & Rail
The rivers, canals and railroads that connected this place between 1830 and 1911.
Notable People
The people born, buried or genuinely tied to this exact place, with their stories.
Historical Maps
Historic maps of the location layered over how it looks today.
Finds & Access
Museum objects tied to the area, and the laws on searching, collecting and access here.
Literature
The old books, county histories and archives that mention this place, quoted with their sources.
Spotlight
A deep dive into the most remarkable, lesser-known history of the place, traced back to the record.
Points of Interest
The most significant historic sites and landmarks near the location, and why they matter.
Timeline
The whole story of the location told era by era, from first peoples to the present day.
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Frequently asked about McHenry

When does McHenry first appear in the US census?
McHenry, Illinois first appears in the federal census in 1840, with a recorded population of 2,578.
What is the population of McHenry?
At the most recent federal census (2020), McHenry had a recorded population of 310,229.
Were any battles fought in McHenry?
2 documented military engagements took place in McHenry, including Skirmish at Buffalo Grove, Buffalo Grove Skirmish.
How many historic places are in McHenry?
29 sites are listed on the National Register of Historic Places in McHenry, Illinois.
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