Allegan is a city in the U.S. state of Michigan. As of the 2000 census, the city population was 4,838. It is the county seat of Allegan County. The city lies within Allegan Township, but is administratively autonomous.
Allegan was named by Michigan historian Henry Rowe Schoolcraft in 1837 to sound like a Native American word. Land was purchased from government to form the downtown business district; village organization came in 1838 with city incorporation authorized in 1907.
Allegan is located in the south-central portion of the county. To the west and northwest is the Allegan State Game Area for which the city is considered a gateway. In all other directions Allegan is surrounded by farmland.