Pennsylvania played a critical role during World War II.  The steel mills in Pittsburgh and Bethlehem ran around the clock making the steel needed to build planes and tanks, and the coal mines produced tons of coal.  All across the state, ordinary people pitched in, collecting scrap metal and rubber and other resources that could aid the military. The farms in the Pennsylvania countryside produced food for the troops.  There were also many military bases in the state, such as Carlisle Barracks, Fort Indiantown Gap, Harrisburg Military Post, Letterkenny Army Depot, New Cumberland Army Depot, and Tobyhanna Army Depot.  Letterkenny was built during World War II to dispose of obsolete or broken weapons.