Allegan County is a county in the U.S. state of Michigan. As of the 2020 United States Census, the population was 120,502. The county seat is Allegan. The name was coined by Henry Rowe Schoolcraft to sound like a Native American word.

Allegan is a city and the county seat of Allegan County, Michigan Its population was 5,222 at the 2020 census. It’s located 40 miles (64 km) southwest of Grand Rapids and 30 miles (48 km) northwest of Kalamazoo, both via US 131. It lies within Allegan Township but is administratively autonomous.