St. Clair County is a county located in the U.S. state of Michigan bordering the west bank of the St. Clair River. As of the 2010 census, the population was 163,040. It is the 13th-most populous county in the state. The county seat is Port Huron, located at the north end of the St. Clair River at Lake Huron. The county was created September 10, 1820, and its government was organized in 1821.
According to the U.S. Census Bureau, the county has a total area of 837 square miles (2,170 km), of which 721 square miles (1,870 km) is land and 115 square miles (300 km) (14%) is water. St. Clair County is one of five counties that form the peninsula, known as the Thumb, that projects into Lake Huron. St. Clair County is closely connected in terms of economy with its neighbors, Metropolitan Detroit and Sanilac County in Michigan, and Lambton County across the river in Ontario, Canada. Saint Clair County is the principal county in The Blue Water Area, a sub-region of the Thumb.
The 2010 United States Census indicates St. Clair County had a 2010 population of 163,040. This is a decrease of -1,195 people from the 2000 United States Census. Overall, the county had a -0.7% growth rate during this ten-year period. In 2010 there were 63,841 households and 44,238 families in the county. The population density was 226.1 per square mile (87.3 square kilometers). There were 71,822 housing units at an average density of 99.6 per square mile (38.5 square kilometers). 93.9% were White, 2.4% Black or African American, 0.5% Asian, 0.4% Native American, 0.7% of some other race and 2.0% of two or more races. 2.9% were Hispanic or Latino (of any race). 25.9% identified as of German, 10.2% Polish, 9.3% Irish, 8.5% English, 6.5% French, 6.5% American, and 5.1% Italian ancestry.
There were 63,841 households out of which 31.3% had children under the age of 18 living with them, 52.9% were opposite-sex families, 11.4% had a female householder with no husband present, 30.7% were non-families, and 25.5% were made up of individuals. The average household size was 2.52 and the average family size was 3.01.
In the county, the population was spread out with 23.7% under age of 18, 8.0% from 18 to 24, 23.8% from 25 to 44, 30.1% from 45 to 64, and 14.5% who were 65 years of age or older. The median age was 41 years. For every 100 females, there were 98.1 males. For every 100 females age 18 and over, there were 95.7 males.
The 2010 American Community Survey 1-year estimate indicates the median income for a household in the county was $44,369 and the median income for a family was $53,207. Males had a median income of $30,056 versus $16,771 for females. The per capita income for the county was $22,390. About 10.4% of families and 15.4% of the population were below the poverty line, including 22.7% of those under the age 18 and 6.8% of those age 65 or over.
St Clair County Michigan neighborhoods include: Blue River Garden Sub, Clinton, Frith Rd, N Riverside, River Ridge, St Clair North, St. Clair Twp.