Illinois

Clark

15,455
2020 population
1820
first census record
21
census records

About Clark

Clark, Illinois, first appears in the United States federal census in 1820, when it recorded a population of 931. At the most recent census, in 2020, its population stood at 15,455.

Its recorded population peaked at 24,033 in 1900, and has since declined by roughly 36 percent.

On the ground today, 9 places are listed on the National Register of Historic Places.

Population by decade

Census YearPopulationChart
202015,455
201016,335
200017,008
199015,921
198016,913
197016,216
196016,546
195017,362
194018,842
193017,872
192021,165
191023,517
190024,033
189021,899
188021,894
187018,719
186014,987
18509,532
18407,453
18303,940
1820931
Source

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

Historic places in Clark

National Register of Historic Places listings in Clark, Illinois.

Old Stone Arch, National Road
Marshall
Dulaney, Robert L., House
Marshall
First Congregational Church
Marshall
Archer House Hotel
Marshall
Old Stone Arch Bridge
Clark Center
Harlan Hall
Marshall
Marshall Business Historic District
Marshall
Lewis, John W., House
Marshall
Manly-McCann House
Marshall

Other counties in Illinois

Explore census history and historic records for more Illinois counties.

McLeanMenardMercerMonroeMontgomeryMorganMoultrieOglePeoriaPerryPiattPikePopePulaskiPutnamRandolphRichlandRock IslandSalineSangamon
Unlimited access

Everything a full report reveals about Clark County, Illinois

This page charts the census history of Clark 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.
First month just $5.99, then $11.99 a month. Unlimited locations, cancel anytime.

Every location is different. Not every section appears for every place, only what the historical record actually holds turns up in a report.

Start your Clark County, Illinois report
Or see a real report first

Explore Illinois records

Illinoishistory ›NRHP historic sites ›Notable people from Illinois›

Frequently asked about Clark

When does Clark first appear in the US census?
Clark, Illinois first appears in the federal census in 1820, with a recorded population of 931.
What is the population of Clark?
At the most recent federal census (2020), Clark had a recorded population of 15,455.
When did Clark's population peak?
Clark's recorded population peaked at 24,033 in 1900.
How many historic places are in Clark?
9 sites are listed on the National Register of Historic Places in Clark, Illinois.
Aubrey Research

Research the history of any US location

Aubrey searches federal archives, archaeological records, historic registers, and primary sources to build a full historical report for any address or place in the United States.

Research your locationView a free sample report