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 1…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.