St. Clair County, Michigan

St. Clair County is a county located in the U.S. state of Michigan and bordering the west bank of the St. Clair River. As of the 2020 census, the population was 160,383. 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. It is located northeast of Detroit. Geographically, it lies in the Thumb area of eastern Michigan.
Etymology.
French explorer René-Robert Cavelier, Sieur de La Salle led an expedition to this area on August 12, 1679. They named the lake as "", because it was the feast day of Saint Clare of Assisi, whom they venerated. English mapmakers adopted the French name, identifying the lake feature as Saint Clare on maps dated as early as 1710. By the Mitchell Map of 1755, the spelling was given as St. Clair, which is the current version. Located along the western shores of Lake St. Clair and the St. Clair River, the county was named for them by European-American settlers.
The name is sometimes mistakenly attributed to honoring Arthur St. Clair, an American Revolutionary War general and governor of the Northwest Territory, but it was established long before he was considered a notable figure. The earlier spelling of the lake's name may have been conflated with English practice and the name of the general, as several political jurisdictions near the lake and the river, such as St. Clair County, St. Clair Township, and the cities of St. Clair and St. Clair Shores, share this spelling (see List of Michigan county name etymologies).
The name has sometimes been mistakenly attributed to honoring Patrick Sinclair, a British officer who purchased land on the St. Clair River at the mouth of the Pine River. In 1764, he built Fort Sinclair there, which was in use for nearly 20 years before being abandoned. As noted, the name was established before he was active in the area.
Geography.
According to the U.S. Census Bureau, the county has a total area of , of which is land and (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, Metro 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. 
Demographics.
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 the 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 of 18 and 6.8% of those age 65 or over.
Government.
The county government operates the jail, maintains rural roads, operates the
major local courts, keeps files of deeds and mortgages, maintains vital records, administers
public health regulations, and participates with the state in the provision of welfare and
other social services. The county board of commissioners controls the
budget but has only limited authority to make laws or ordinances. In Michigan, most local
government functions — police and fire, building and zoning, tax assessment, street
maintenance, etc. — are the responsibility of individual cities and townships.
Parks.
St. Clair County is home to five county parks: Columbus County Park, Fort Gratiot County Park, Fort Gratiot Light station, Goodells County Park, and Woodsong County Park. St. Clair County also operates the Wadhams to Avoca Trail and works with local units of government to develop the Bridge to Bay Trail.