County Maps US

St. Clair County, Michigan

A county in Michigan, ranked 13 of 83 by population.

CountyFIPS 26147

Within Michigan
St. Clair County, highlighted, with the areas around it. Boundaries generalised from the 2025 Census cartographic boundary file; neighbour fills carry no data. The dot marks Port Huron, the county seat, located via the 2025 Census Gazetteer.

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Population
160,486
+100 (+0.1%) since 2020
Land area
721.5
square miles. A further 13.7% of the total area is water
Population density
222
people per square mile, computed rather than published
County seat
Port Huron
Seat of county government.
Established
1820
205 years ago
Largest city
Port Huron city
Population 28,273.

Sources: US Census Bureau, Population Estimates Program, Vintage 2025 Population Estimates, released 26 March 2026; US Census Bureau, Gazetteer Files, 2025 Gazetteer Files, released 10 September 2025; Wikidata (CC0), Wikidata. Retrieved 30 August 2026.

Satellite view

Aerial imagery of St. Clair County with its boundary drawn on top. A map shows you the shape; this shows you what is inside it, and which side of the line a place falls on.

Aerial view of St. Clair County, Michigan from the USGS National Map, with its boundary outlined
Imagery: USGS National Map, USGS Imagery Only, public domain, requested from USGS by your browser when you reach this point on the page, at 558 by 800 pixels. The boundary is the 2025 Census cartographic boundary file, reprojected to Web Mercator to match the imagery. You can also open the USGS National Map viewer.

Where St. Clair County ranks

Position among the 83 counties of Michigan, and among all 3,144 US counties and county-equivalents. Computed from the figures on this page.

MeasureValueIn MichiganNationally
Population160,48613th of 83438th of 3,144
Land area721.5 sq mi24th of 831,239th of 3,144
Population density222 per sq mi17th of 83533rd of 3,144
Median household income$71,27022nd of 831,110th of 3,143

Full data for St. Clair County

Every figure below is attributed to the Census Bureau product it came from, with the vintage of that product.
MeasureValueSource and vintage
Population160,486Vintage 2025 Population Estimates
Population in 2020160,386Vintage 2025 Population Estimates
2020 estimates base?160,385Vintage 2025 Population Estimates
Land area721.5 sq mi2025 Gazetteer Files
Water area115 sq mi2025 Gazetteer Files
Total area836.5 sq mi2025 Gazetteer Files
Population density?222 per sq miComputed: Vintage 2025 estimates divided by 2025 Gazetteer land area
Median household income$71,270American Community Survey 2020-2024 5-Year Estimates
Median home value$224,600American Community Survey 2020-2024 5-Year Estimates
Median age44.5American Community Survey 2020-2024 5-Year Estimates
Households67,816American Community Survey 2020-2024 5-Year Estimates
Housing units72,799American Community Survey 2020-2024 5-Year Estimates

Sources: US Census Bureau, Population Estimates Program, Vintage 2025 Population Estimates, released 26 March 2026; US Census Bureau, Gazetteer Files, 2025 Gazetteer Files, released 10 September 2025; US Census Bureau, American Community Survey, American Community Survey 2020-2024 5-Year Estimates, released 29 January 2026. Population density is computed here, not published: it divides the Vintage 2025 population estimate by the 2025 Gazetteer land area, which are two different Census products. Retrieved 30 August 2026.

How the population changed

The Census Bureau publishes the components behind an estimate, not just the total. For the year to July 2025:

Births minus deaths
-461
1,447 births, 1,908 deaths
Net migration
+638
More people moved in than moved out.

Source: US Census Bureau, Population Estimates Program, Vintage 2025 Population Estimates, released 26 March 2026. Retrieved 30 August 2026.

The 3 areas bordering St. Clair County

Ordered by the length of the border actually shared, which the Census Bureau publishes in its county adjacency file and which no other county reference presents.

Bordering areaStateShared borderPopulation
Macomb CountyMichigan42 mi886,221
Sanilac CountyMichigan33 mi40,083
Lapeer CountyMichigan18 mi89,516

Source: US Census Bureau, County Adjacency File, 2025 County Adjacency File, released 15 September 2025. Retrieved 30 August 2026.

All 83 counties of Michigan

Open the interactive Michigan county map, or jump straight to any of them.

Data on this page last rebuilt 30 August 2026. How these figures are produced.