[1] 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.

[1][5] 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.

The county government operates the jail, maintains rural roads, operates the major local courts, records deeds, mortgages, and vital records, administers public health regulations, and participates with the state in the provision of social services.

The county board of commissioners controls the budget and has limited authority to make laws or ordinances.

In Michigan, most local government functions — police and fire, building and zoning, tax assessment, street maintenance, etc.