Missouri

St. Clair

9,284
2020 population
1850
first census record
18
census records

About St. Clair

St. Clair, Missouri, first appears in the United States federal census in 1850, when it recorded a population of 3,556. At the most recent census, in 2020, its population stood at 9,284.

Its recorded population peaked at 17,907 in 1900, and has since declined by roughly 48 percent.

On the ground today, 7 documented military engagements have been recorded within the county, among them Haun's Mill Massacre, Raid on Osceola (Lane), Sacking of Osceola, Missouri, and 3 places are listed on the National Register of Historic Places.

Population by decade

Census YearPopulationChart
20209,284
20109,805
20009,652
19908,457
19808,622
19707,667
19608,421
195010,482
194013,146
193013,289
192015,341
191016,412
190017,907
189016,747
188014,125
18706,742
18606,812
18503,556
Source

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

Battles & engagements in St. Clair

Military engagements that took place in St. Clair, Missouri.

Haun's Mill Massacre
1838
Raid on Osceola (Lane)
1861
Sacking of Osceola, Missouri
1861
Osceola Raid
1861
Sacking of Osceola – Lane's Jayhawkers
1861
Osceola Missouri
1861
Skirmish at Osceola (guerrilla, 1863)
1863

Historic places in St. Clair

National Register of Historic Places listings in St. Clair, Missouri.

Osceola Public School Building
Osceola
Browse all Missourihistoric sites ›

Other counties in Missouri

Explore census history and historic records for more Missouri counties.

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Everything a full report reveals about St. Clair County, Missouri

This page charts the census history of St. Clair County, Missouri. 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 St. Clair

When does St. Clair first appear in the US census?
St. Clair, Missouri first appears in the federal census in 1850, with a recorded population of 3,556.
What is the population of St. Clair?
At the most recent federal census (2020), St. Clair had a recorded population of 9,284.
When did St. Clair's population peak?
St. Clair's recorded population peaked at 17,907 in 1900.
Were any battles fought in St. Clair?
7 documented military engagements took place in St. Clair, including Haun's Mill Massacre, Raid on Osceola (Lane), Sacking of Osceola, Missouri.
How many historic places are in St. Clair?
3 sites are listed on the National Register of Historic Places in St. Clair, Missouri.
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