Sanilac County is a county located in the U.S. state of Michigan. As of the 2010 census, the population was 43,114. The county seat is Sandusky. The county was created on September 10, 1822, and was fully organized on December 31, 1849
According to the U.S. Census Bureau, the county has a total area of 1,590 square miles (4,100 km), of which 963 square miles (2,490 km) is land and 627 square miles (1,620 km) (39%) is water.
The 2010 United States Census indicates Sanilac County had a 2010 population of 43,114. This decrease of -1,433 people from the 2000 United States Census represents a 3.2% population loss in the decade. In 2010 there were 17,132 households and 11,885 families in the county. The population density was 44.8 per square mile (17.3 per km²). There were 22,725 housing units at an average density of 23.6 per square mile (9.1 per km²). 96.6% of the population were White, 0.5% Native American, 0.3% Black or African American, 0.3% Asian, 1.1% of some other race and 1.2% of two or more races. 3.3% were Hispanic or Latino (of any race). 26.1% were of German, 11.0% Polish, 10.4% English, 8.3% Irish, 7.2% American and 5.1% French, French Canadian or Cajun ancestry.
There were 17,132 households out of which 29.2% had children under the age of 18 living with them, 55.3% were husband and wife families, 9.8% had a female householder with no husband present, 30.6% were non-families, and 26.4% were made up of individuals. The average household size was 2.48 and the average family size was 2.97.
In the county, the population was spread out with 23.6% under age of 18, 7.4% from 18 to 24, 21.8% from 25 to 44, 29.6% from 45 to 64, and 17.6% who were 65 years of age or older. The median age was 43 years. For every 100 females there were 97.8 males. For every 100 females age 18 and over, there were 96.7 males.
The 2010 American Community Survey 3-year estimate indicates the median income for a household in the county was $39,138 and the median income for a family was $47,885. Males had a median income of $27,440 versus $16,509 for females. The per capita income for the county was $19,671. About 1.5% of families and 16.1% of the population were below the poverty line, including 23.3% of those under the age 18 and 11.4% of those age 65 or over.