The first B-24 bomber rolls off the assembly line at the Willow Run Bomber Plant near Ypsilanti. In December 1940, the federal government asked the Ford Motor Company to build 1,200 B-24 bombers. Ford's chief engineer, Charles Sorensen, quickly devised a then-untried scheme of mass-producing planes. The government agreed to the plan, and in April 1941, construction began on what would become the world's largest assembly plant. The plant produced 8,600 planes. By early 1944, bombers came off Willow Run's mile-long assembly line at the rate of one an hour. Michigan's other auto companies also produced war materiel. By the end of World War II, Chrysler's Warren Tank Plant made 25,000 tanks, while in Kingsford, the Ford Motor Company manufactured more than 4,000 gliders. Known as the "Arsenal of Democracy," Michigan—with only 4 percent of the nation's population—led all other states in the production of war materiel.

• Learn more about the B-24 bomber:
• visit the Michigan Historical Museum in person
• see the online version of the museum's Arsenal of Democracy Gallery

Updated 06/23/2011