How many people live in St. Clair County, MI?
Updated Apr. 6, 2026Refreshed annually
In 2024, there were about 160,300 people living in St. Clair County, MI. That makes St. Clair County the 13th-most populous county in Michigan. It is home to 1.6% of people living in the state.
160K
population of St. Clair County, MI (2024)
1.6%
County share of the Michigan population (2024)
About 160,300 people lived in St. Clair County, MI in 2024.
Population estimates, 2000–2024
What are St. Clair County, MI’s age demographics?
About 34,700 St. Clair County, MI residents are aged 65 and older in 2024. That represents 21.7% of its population. For comparison, the age group represents 19.6% of Michigan’s population and 18% in the US overall.
Another 31,600 St. Clair County residents, or 19.7% of the population, were children under 18. For comparison, the age group represents 20.8% of Michigan’s population and 21.6% in the US overall.
A lower share of St. Clair County, MI's population is aged 25–44 than the US as a whole.
Population estimates by age group, (2024)
What are St. Clair County, MI’s racial and ethnic demographics?
Non-Hispanic white residents make up 90.2% of the St. Clair County, MI population, higher than the national share of 57.5%.
In contrast, St. Clair County’s Hispanic population accounts for 3.9%, below the 20% nationwide, and the non-Hispanic Black or African American population makes up 2.5% of the county, compared with 12.6% nationally.
Racial and ethnic make up differ based on location. These figures reflect how people identified their race alone (not in combination with other races), and separate out Hispanic or Latino ethnicity, following Census reporting standards.
St. Clair County, MI has a higher share of a non-Hispanic white population than Michigan as a whole.
Population estimates by race and ethnicity, (2024)
The largest city or town in St. Clair County, MI is Port Huron with about 28,300 residents in 2024.
Cities and towns in St. Clair County, MI ranked by population
Population (2024), includes only portions within county
| City or town | Population | |
|---|---|---|
| 1. | Port Huron | 28,342 |
| 2. | Fort Gratiot | 11,693 |
| 3. | Port Huron | 10,669 |
| 4. | Marysville | 9,868 |
| 5. | Kimball | 9,625 |
| 6. | Clay | 8,277 |
| 7. | St. Clair | 7,130 |
| 8. | St. Clair | 5,824 |
| 9. | Clyde | 5,431 |
| 10. | Ira | 5,084 |
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Methodology
USAFacts standardizes data, in areas such as time and demographics, to make it easier to understand and compare.
The analysis was generated with the help of AI and reviewed by USAFacts for accuracy.
Page sources
USAFacts endeavors to share the most up-to-date information available. We sourced the data on this page directly from government agencies; however, the intervals at which agencies publish updated data vary.
