Founded in 1820, St. Clair County is one of 83 counties in the state of Michigan. Historically, St. Clair County was formed from part of Macomb County. The city of Port Huron is the county seat. With FIPS code of 147, St. Clair County has a population of 160,053 and area of 837 square miles (2,168 km2).
List of all cities in Saint Clair County, MI alphabetically
| City/Town | Postal Code | Area Code |
| Algonac, MI | 48001 | 810 |
| Allenton, MI | 48002 | 810 |
| Anchorville, MI | 48004 | 810 |
| Avoca, MI | 48006 | 810 |
| Berlin, MI | 48002 | 810 |
| Berlin Township, MI | 48002 | 810 |
| Berville, MI | 48002 | 810 |
| Brockway, MI | 48097 | 810 |
| Burtchville, MI | 48059 | 810 |
| Capac, MI | 48014 | 810 |
| Casco, MI | 48064 | 810 |
| China, MI | 48054 | 810 |
| Clay, MI | 48001 | 810 |
| Clyde, MI | 48049 | 810 |
| Columbus, MI | 48063 | 810 |
| Cottrellville, MI | 48039 | 810 |
| East China, MI | 48054 | 810 |
| Emmett, MI | 48022 | 810 |
| Fair Haven, MI | 48023 | 810 |
| Fargo, MI | 48006 | 810 |
| Fort Gratiot, MI | 48059 | 810 |
| Goodells, MI | 48027 | 810 |
| Greenwood, MI | 48006 | 810 |
| Harsens Island, MI | 48028 | 810 |
| Ira, MI | 48023 | 810 |
| Jeddo, MI | 48032 | 810 |
| Kenockee, MI | 48006 | 810 |
| Kimball, MI | 48074 | 810 |
| Lakeport, MI | 48059 | 810 |
| Lynn, MI | 48097 | 810 |
| Marine City, MI | 48039 | 810 |
| Marysville, MI | 48040 | 810 |
| Memphis, MI | 48041 | 810 |
| Mussey, MI | 48014 | 810 |
| North Lakeport, MI | 48059 | 810 |
| North Street, MI | 48049 | 810 |
| Pearl Beach, MI | 48001 | 810 |
| Port Huron, MI | 48060 | 810 |
| 48061 | 810 | |
| Riley, MI | 48041 | 810 |
| Ruby, MI | 48049 | 810 |
| Russell Island, MI | 48001 | 810 |
| Saint Clair, MI | 48079 | 810 |
| Smiths Creek, MI | 48074 | 810 |
| Wales, MI | 48027 | 810 |
| Worth Township, MI | 48032 | 810 |
| Yale, MI | 48097 | 810 |