Plainwell is a city in Allegan County in the U.S. state of Michigan. The population was 3,804 at the 2010 census.Plainwell is located on M-89 just east of its junction with US 131. The city of Otsego is about three miles to the west. Kalamazoo is about ten miles to the south and Grand Rapids about 35 miles north. The Kalamazoo River flows through the center of the city.Plainwell is the birthplace of syndicated cartoonist Dave Coverly, creator of the Speed Bump comic strip, actor Ed Gale, famous for his role as Howard the Duck in the movie of the same name.Though it sounds somewhat common, there are no other communities named Plainwell anywhere in the United States. It is known as The Island City.