Roscommon County has a population of 23,459, according to the 2020 census. The county was founded in 1840 and organized in 1875. The county was formed by the Michigan Legislature in 1840 as Mikenauk County, then renamed Roscommon County in 1843. It was administered by Michilimackinac (Mackinac), Cheboygan, and Midland counties, in succession, prior to the organization of county government in 1875. Roscommon County was named after County Roscommon, Ireland.
During prehistoric times, glacial action helped shape the Michigan-area terrain. A large portion of the area is the Grayling outwash plain, which includes sandy ice-disintegration ridges; jack pine barrens, white pine-red pine forest, and northern hardwood forest. Large lakes were created by glacial action.
Prominent geographic features include:
- Au Sable River
- Backus Creek
- Cut River
- Dead Stream Flooding
- Higgins Lake
- Houghton Lake
- Houghton Lake Flats
- Lake St. Helen
- Marl Lake
Roscommon County is home to South Higgins Lake State Park.