Bay County is a county located in the State of Michigan. It is located within a unique and diverse ecological area within Michigan. It is part of the Saginaw Bay watershed. The Saginaw Bay watershed is Michigan's largest watershed (8,709 square miles), including a part of 22 counties. The bay contains sections of white sandy beach shorelines as well as freshwater coastal wetland areas. The watershed drains approximately 15% of Michigan's total land area.
Bay County comprises the Bay City, MI Metropolitan Statistical Area, which is included in the Saginaw-Midland-Bay City, MI Combined Statistical Area. It is also considered to be part of the Flint/Tri-Cities region.
Bay County was created in 1857 from portions of Midland County, Saginaw County and Arenac County. Its name origin is that it "surrounds Saginaw Bay. Being only sparsely populated at that time, Arenac County government was unorganized and was attached to Saginaw County for administrative purposes. There was considerable opposition to the creation of Bay County from elected officials in both Saginaw and Midland counties. In 1854, a bill introduced to the state legislature to create Bay County was defeated by a small majority.