The point is that it wasn't just us borrowing more money. We did that for 12 years with no real success. The war brought huge amounts of demand for our goods from all over the world.
No, the war brought huge amount of demand for goods from the U.S. Government, which wanted tanks and fighters and artillery shells. This demand created full employment and economic rebound - during the war. Even - gasp! - women were sucked into the labor force.
After the war, the U.S. was in a great position to supply the world, having an economy running at full steam and no war damage to repair. But the Great Depression ended as war began, due to demand for military equipment.
