The name purportedly means "the mirage or reflecting river" and the original Indian name was "Kikalamazoo".

As of the 2000 United States census,[13] there were 238,603 people, 93,479 households, and 57,956 families living in the county.

It swung particularly heavily to the Democrats after 2008, following the trend in most urban counties across the country.

Even as Michigan trended Republican in 2016, Kalamazoo County voted for Democratic candidate to a similar level as in recent years.

The county government operates the jail, provides law enforcement in unincorporated areas, maintains rural roads, operates the major local courts, keeps files of deeds and mortgages, maintains vital records, administers public health regulations, and participates with the state in the provision of welfare and other social services.

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

In Michigan, most local government functions—fire, building and zoning, tax assessment, street maintenance, etc.—are the responsibility of individual cities and townships.