
St Clair County
- State:
- Michigan
- County Seat:
- Port Huron
St. Clair County's estimated 2025 population is 160,286 with a growth rate of 0.13% in the past year according to the most recent United States census data. St. Clair County is the 13th largest county in Michigan. The 2010 population was 162,688 and has seen a growth of -1.48% since that time.