[6] French explorer René-Robert Cavelier, Sieur de La Salle led an expedition to this area on August 12, 1679.

They named the lake as Lac Sainte-Claire, because it was the feast day of Saint Clare of Assisi, whom they venerated.

[1][7] English mapmakers adopted the French name, identifying the lake feature as Saint Clare on maps dated as early as 1710.

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 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.

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.

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.