Montmorency County is a county located in Michigan. As of the 2020 Census, the population was 9,153, making it the second-least populous county in Michigan's Lower Peninsula, behind its southern neighbor, Oscoda County. The county seat is Atlanta.
Montmorency County is part of Northern Michigan, and is part of the Lake Huron watershed. The Thunder Bay River, which drains much of the county, flows to Lake Huron's Thunder Bay at Alpena.
The county was created by the Michigan Legislature in 1840 as Cheonoquet County, after a well-known Chippewa Chief, whose name meant Big Cloud. Cheonoquet took part in Indian treaties in 1807, 1815, 1825 and 1837. Renamed Montmorency County on March 8, 1843, it was originally spelled Montmorenci. The name Montmorency probably means Mountain Moor. Montmorency is a boggy land or moor that is at the top of a broad mount or highland. When the county was organized in 1881, some land area was taken from Cheboygan and Alpena counties. Brush Creek, now known as Hillman, was the first county seat. In 1891 the county seat was moved to Atlanta.
According to the U.S. Census Bureau, the county has a total area of 563 square miles, of which 547 square miles is land and 16 square miles (2.8%) is water. Although it lies on Michigan's Lower Peninsula, Montmorency County is considered to be part of Northern Michigan.
Most of the county is covered by state forest land. There is an abundance of lakes, such as Long Lake. Glaciers shaped the area, creating a unique regional ecosystem. A large portion of the area is the Grayling outwash plain, a broad outwash plain including sandy ice-disintegration ridges, jack pine barrens, some white pine-red pine forest, and northern hardwood forest. Large lakes were created by glacial action.