Willow Run, also known as Air Force Plant 31, was a manufacturing complex in Michigan, United States, located between Ypsilanti Township and Belleville, built by the Ford Motor Company to manufacture aircraft, especially the Consolidated B-24 Liberator heavy bomber. Construction of the Willow Run Bomber Plant began in 1940 and was completed in 1942.

Ypsilanti Charter Township is a charter township of Washtenaw County in the U.S. state of Michigan. The population was 55,670 at the 2020 census. The city of Ypsilanti is mostly surrounded by the township, but the two are administered autonomously.