The threat of war in 1940 transformed the farming town of Elwood into a munitions manufacturing hub when the War Department acquired 40,000 acres and built two massive plants to assemble bombs and shells. The factories employed more than 20,000 people, and Route 66 carried workers from nearby cities and provided a corridor for shipments. During World War II, women entered the workforce in unprecedented numbers, and the fictional icon Rosie the Riveter, introduced in a 1942 radio hit song, came to represent female factory workers. In the early hours of June 5, 1942, an explosion at the Elwood plant rattled windows 100 miles away and became the deadliest ordnance plant disaster of World War II, injuring 67 workers and killing 48, with the remains of 16 never found; for welder Emil Novak of Coal City, only his wallet was found. In 1993, the Army declared the arsenal surplus property, and Abraham Lincoln National Cemetery and Midewin National Tallgrass Prairie were established; Midewin is a Potawatomi word for "healing."