Illinois

Cook

5,275,541
2020 population
1840
first census record
19
census records

About Cook

Cook, Illinois, first appears in the United States federal census in 1840, when it recorded a population of 10,201. At the most recent census, in 2020, its population stood at 5,275,541.

Its recorded population peaked at 5,492,369 in 1970, and has since declined by roughly 4 percent.

On the ground today, 24 documented military engagements have been recorded within the county, among them Blue Island Ossuary, Langford Tradition Conflict – Chicago Area, Huber Phase Conflict – Illinois, and 617 places are listed on the National Register of Historic Places.

Population by decade

Census YearPopulationChart
20205,275,541
20105,194,675
20005,376,741
19905,105,067
19805,253,655
19705,492,369
19605,129,725
19504,508,792
19404,063,342
19303,982,123
19203,053,017
19102,405,233
19001,838,735
18901,191,922
1880607,524
1870349,966
1860144,954
185043,385
184010,201
Source

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

Battles & engagements in Cook

Military engagements that took place in Cook, Illinois.

Blue Island Ossuary
1200
Langford Tradition Conflict – Chicago Area
1300
Huber Phase Conflict – Illinois
1400
Fort Dearborn Massacre August 15 1812
1812
Battle of Fort Dearborn (Chicago Massacre)
1812
Fort Dearborn — Evacuation Route Ambush 1812
1812
Battle of Fort Dearborn — Chicago Massacre
1812
Fort Dearborn Massacre
1812
Skirmish at Fort Dearborn area
1813
Skirmish at Turtle Village / Potawatomi Conflict
1832
Fort Dearborn Area Skirmishes (1832)
1832
Treaty of Chicago — Potawatomi Land Cession (1833)
1833
Camp Douglas — Confederate Prison Conspiracies
1862
Camp Douglas Prison Operations
1862
Confederate Northwest Conspiracy 1864
1864
Camp Douglas Confederate Escape Plot
1864
Reno Court of Inquiry 1879
1879
Haymarket Affair, Chicago 1886
1886
Pullman Strike – Blue Island Violence
1894
Pullman Strike — Battle of the Rock Island Crossing
1894
Red Summer — Chicago Race Riot 1919
1919
Red Summer — Chicago Race Riot (1919)
1919
Republic Steel Massacre (Chicago 1937)
1937
Nike Missile Defense Ring — Chicago (C-Series Batteries)
1955

Historic places in Cook

National Register of Historic Places listings in Cook, Illinois.

Haymarket Martyrs' Monument
Forest Park
Grosse Point Light Station
Evanston
Peoples Gas Building
Chicago
Pattington Apartments
Chicago
Fountain Plaza Apartments
Evanston
St. James Catholic Church and Cemetery
Lemont
Madlener, Albert F., House
Chicago
Auditorium Building, Roosevelt University
Chicago
Pullman Historic District
Chicago
Edison Park
Chicago
Old Town Triangle Historic District
Chicago
Lathrop, Julia C., Homes
Chicago
Chicago and Northwestern Depot
Wilmette
One LaSalle Street Building
Chicago
Evanston Ridge Historic District
Evanston
Calumet Plant, R. R. Donnelly & Sons Company
Chicago
Robertson, John, Jr., House
Barrington
Building at 417-419 Lee Street
Evanston
Riis, Jacob A., Park
Chicago
South Shore Country Club
Chicago
Shedd Park Fieldhouse
Chicago
West Argyle Street Historic District
Chicago
Montgomery, John Rogerson, House
Glencoe
Frangenheim, William, House
Maywood
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 Cook County, Illinois

This page charts the census history of Cook 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 Cook

When does Cook first appear in the US census?
Cook, Illinois first appears in the federal census in 1840, with a recorded population of 10,201.
What is the population of Cook?
At the most recent federal census (2020), Cook had a recorded population of 5,275,541.
When did Cook's population peak?
Cook's recorded population peaked at 5,492,369 in 1970.
Were any battles fought in Cook?
24 documented military engagements took place in Cook, including Blue Island Ossuary, Langford Tradition Conflict – Chicago Area, Huber Phase Conflict – Illinois.
How many historic places are in Cook?
617 sites are listed on the National Register of Historic Places in Cook, Illinois.
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