St. Clair County is a county in Michigan, United States, forming the state’s easternmost point along the St. Clair River across from Sarnia, Ontario. It had a population of 160,383 at the 2020 census and covers 837 square miles (2,170 km2), of which 721 square miles (1,870 km2) are land, centred near 42°56′N 82°40′W.
Port Huron is the county seat and its postal code is 48060. The county has 6 cities, 2 villages, 3 census-designated places, and more than 50 unincorporated communities, organized across 19 civil townships. It sits in the Eastern time zone and forms most of the peninsula Michiganders call The Thumb, also known locally as the Blue Water Area.
Towns & Villages in St. Clair County
The table below lists every incorporated city and village, the three census-designated places, and the unincorporated communities carried over from county records. Cities are self-governing and sit outside township government in Michigan; villages remain part of the township that surrounds them. Type key: City = independent city; City · seat = county seat; Village = incorporated village inside a township; CDP = census-designated place; Unincorp. = unincorporated community or crossroads.
| Place | Type | Township | Pop. | ZIP |
|---|---|---|---|---|
| Port Huron | City · seat | — | 28,921 | 48060 |
| Marysville | City | — | — | 48040 |
| Marine City | City | — | — | 48039 |
| St. Clair | City | — | — | 48079 |
| Algonac | City | — | — | 48001 |
| Yale | City | — | — | 48097 |
| Capac | Village | — | — | 48014 |
| Emmett | Village | Emmett Twp. | — | 48022 |
| Lakeport | CDP | Burtchville Twp. | — | 48059 |
| Pearl Beach | CDP | Ira Twp. | — | — |
| Ruby | CDP | — | — | 48078 |
| Abbottsford | Unincorp. | — | — | — |
| Adair | Unincorp. | — | — | — |
| Allenton | Unincorp. | — | — | — |
| Anchorville | Unincorp. | Ira Twp. | — | — |
| Atkins | Unincorp. | — | — | — |
| Avalon Beach | Unincorp. | — | — | — |
| Avoca | Unincorp. | — | — | — |
| Bedore | Unincorp. | — | — | — |
| Belle River | Unincorp. | China Twp. | — | — |
| Berville | Unincorp. | — | — | — |
| Blaine | Unincorp. | — | — | — |
| Broadbridge Station | Unincorp. | — | — | — |
| Brockway | Unincorp. | Brockway Twp. | — | — |
| Casco | Unincorp. | Casco Twp. | — | — |
| Cherry Beach | Unincorp. | — | — | — |
| Clays Landing | Unincorp. | — | — | — |
| Columbus | Unincorp. | Columbus Twp. | — | 48063 |
| Copeland Corner | Unincorp. | — | — | — |
| Fair Haven | Unincorp. | Ira Twp. | — | 48023 |
| Fargo | Unincorp. | — | — | — |
| Forster | Unincorp. | — | — | — |
| Gardendale | Unincorp. | — | — | — |
| Goodells | Unincorp. | Kenockee Twp. | — | 48027 |
| Grande Pointe | Unincorp. | — | — | — |
| Hawthorne | Unincorp. | — | — | — |
| Jeddo | Unincorp. | Grant Twp. | — | 48032 |
| Keewahdin | Unincorp. | — | — | — |
| Lambs | Unincorp. | — | — | — |
| Lesterville | Unincorp. | — | — | — |
| Maple Leaf | Unincorp. | — | — | — |
| Martindale Beach | Unincorp. | — | — | — |
| Memphis (part) | Unincorp. | Riley Twp. | — | 48041 |
| Miller | Unincorp. | — | — | — |
| Muirs | Unincorp. | — | — | — |
| Muttonville | Unincorp. | — | — | — |
| North Lakeport | Unincorp. | Burtchville Twp. | — | — |
| Perch Point | Unincorp. | — | — | — |
| Peters | Unincorp. | — | — | — |
| Pointe aux Chenes | Unincorp. | — | — | — |
| Pointe aux Tremble | Unincorp. | — | — | — |
| Rattle Run | Unincorp. | — | — | — |
| Riley Center | Unincorp. | Riley Twp. | — | — |
| Riverside | Unincorp. | — | — | — |
| Roberts Landing | Unincorp. | — | — | — |
| Sans Souci | Unincorp. | — | — | — |
| Smiths Creek | Unincorp. | Kimball Twp. | — | 48074 |
| Snyderville | Unincorp. | — | — | — |
| South Park | Unincorp. | — | — | — |
| Sparlingville | Unincorp. | — | — | — |
| Starville | Unincorp. | — | — | — |
| Tappan | Unincorp. | — | — | — |
| Thornton | Unincorp. | — | — | — |
| Wadhams | Unincorp. | Kimball Twp. | — | — |
| Wales Center | Unincorp. | Wales Twp. | — | — |
| West Tappan | Unincorp. | — | — | — |
Memphis is listed as a partial entry because the city straddles the St. Clair, Macomb and Lapeer county lines; only its St. Clair County portion, in Riley Township, is covered here. Individual place-level 2020 census counts were not independently verified for this rewrite beyond Port Huron and are shown as a dash rather than guessed.
Townships
| Township | Pop. (2020) | Main settlements |
|---|---|---|
| Berlin Twp. | — | Capac (part) |
| Brockway Twp. | — | Brockway, Yale (part) |
| Burtchville Twp. | — | Lakeport, North Lakeport |
| Casco Twp. | — | Casco, Cherry Beach |
| China Twp. | — | Belle River, Pointe aux Chenes |
| Clay Twp. | — | Algonac (adjacent), Harsens Island |
| Clyde Twp. | — | Wadhams (part), Peters |
| Columbus Twp. | — | Columbus |
| Cottrellville Twp. | — | Fair Haven (adjacent), Anchorville (part) |
| Emmett Twp. | — | Emmett |
| Grant Twp. | — | Jeddo |
| Greenwood Twp. | — | Allenton (part) |
| Ira Twp. | — | Fair Haven, Anchorville, Pearl Beach |
| Kenockee Twp. | — | Goodells |
| Kimball Twp. | — | Smiths Creek, Wadhams |
| Lynn Twp. | — | Avoca (part) |
| Mussey Twp. | — | Muttonville |
| Riley Twp. | — | Riley Center, Memphis (part) |
| St. Clair Twp. | — | St. Clair (adjacent), Starville |
| Wales Twp. | — | Wales Center, West Tappan |
ZIP Codes
- 48060 — Port Huron
- 48040 — Marysville
- 48039 — Marine City
- 48079 — St. Clair
- 48001 — Algonac
- 48097 — Yale
- 48014 — Capac (also serves Berlin Township)
- 48022 — Emmett
- 48059 — Lakeport (also serves Burtchville Township)
- 48078 — Ruby (also serves parts of Kenockee and Emmett townships)
- 48063 — Columbus
- 48023 — Fair Haven
- 48027 — Goodells
- 48032 — Jeddo
- 48074 — Smiths Creek
- 48041 — Memphis
Most of the remaining unincorporated crossroads and beach communities use the ZIP code of their nearest post office town rather than a code of their own.
Geography
St. Clair County occupies the tip of Michigan’s Thumb, bounded on the east by the St. Clair River and Lake St. Clair, which together form the international border with Ontario, Canada. The county is largely flat glacial till plain, drained toward the river by the Belle and Black rivers and their tributaries. Harsens Island, in the St. Clair River delta, is part of Clay Township and reachable only by ferry. The county borders Sanilac County to the north, Lapeer County to the west, and Macomb County to the south; Lambton County, Ontario lies directly across the river and lake to the east.
Demographics
St. Clair County had 160,383 residents at the 2020 census, spread across 72,092 housing units, for a density of about 222 people per square mile of land. Port Huron is the largest city and Marysville the second largest. The county’s population is 90.1% white, 5.6% two or more races, 3.4% Hispanic or Latino of any race, and 2.5% Black or African American. County-level median household income was not independently re-verified for this rewrite; the statewide Michigan median is $69,183.
Economy & Local Life
Port Huron’s location at the mouth of the St. Clair River and the terminus of Interstates 69 and 94 makes cross-border trade with Sarnia, Ontario, via the Blue Water Bridge, a defining part of the county economy. Manufacturing, chemical processing, and auto-parts supply plants cluster around Port Huron and Marysville, while the rural townships to the west support dairy and corn farming. The riverfront towns — Marine City, Algonac, and St. Clair — lean on boating, marinas, and Great Lakes freighter-watching tourism; the annual Port Huron-to-Mackinac sailboat race starts on the St. Clair River each July.
History
St. Clair County was created on March 28, 1820, and organized in 1821, taking its name from Lake St. Clair, itself named by French explorer René-Robert Cavelier, Sieur de La Salle, on August 12, 1679, for the feast day of Saint Clare of Assisi. Fort Gratiot, built near present-day Port Huron in 1814, was one of the first American military posts on the upper Great Lakes frontier after the War of 1812. Inventor Thomas Edison spent much of his boyhood in Port Huron, where a museum and the restored Fort Gratiot Light now mark the connection. The Blue Water Bridge, opened in 1938 and later twinned in 1997, remains one of the busiest US–Canada crossings on the Great Lakes.
Getting There
Interstates 69 and 94 both terminate at the Blue Water Bridge in Port Huron, and state routes M-19, M-25, M-29, M-136, and M-154 connect the county’s smaller towns.
- Detroit — 60 miles southwest
- Flint — 55 miles west
- Sarnia, Ontario — across the Blue Water Bridge
- Lansing — 115 miles west
The nearest large commercial airport is Detroit Metropolitan Wayne County Airport (DTW), about 65 miles southwest. Amtrak’s Blue Water line connects Port Huron to Chicago via Flint and East Lansing.
Frequently Asked Questions
Where is St. Clair County, Michigan?
It occupies the tip of Michigan’s Thumb in the state’s east-central part, along the St. Clair River across from Sarnia, Ontario, and northeast of Detroit.
What is the population of St. Clair County?
160,383 at the 2020 census.
How big is St. Clair County?
837 square miles (2,170 km2) in total, 721 square miles (1,870 km2) of it land.
What is the county seat of St. Clair County?
Port Huron is the county seat.
How many towns are in St. Clair County?
Six cities, two villages, three census-designated places, and more than 50 smaller unincorporated communities across 19 townships.
What ZIP codes are in St. Clair County?
Port Huron uses 48060; other main towns include Marysville 48040, Marine City 48039, St. Clair 48079, Algonac 48001, and Yale 48097.
Why is St. Clair County called the Blue Water Area?
The nickname comes from the clear, fast-flowing St. Clair River connecting Lake Huron to Lake St. Clair along the county’s eastern edge.
More counties in this state: Towns and villages in Michigan.