Isabella County, Michigan: History
Isabella County was described by action of the Michigan Territory legislature in 1831, but for purposes of population, revenue, and judicial matters, it was assigned to nearby counties. Its area was partitioned from unorganized territory plus a portion of Mackinac, which had existed as a Territorial County since 1818.
The Michigan Territory was admitted to the Union as Michigan state in early 1837. By 1859, Isabella had sufficient settlement and interest in self-government that the state legislature authorized its organization. Based on a suggestion by Henry Rowe Schoolcraft, the U.S. Indian agent in this area, the county was named after Queen Isabella I of Castile, who with her husband Ferdinand commissioned Columbus's expedition to the New World.
Isabella County comprises the Mount Pleasant, Michigan micropolitan statistical area in Mid-Michigan. The county contains the Isabella Indian Reservation, which has a total area of 217.67 square miles (563.8 km2). It is the major land base of the federally recognized Saginaw Chippewa Tribal Nation. Part of the county seat of Mount Pleasant is located within the reservation.