Well, before Pearl Harbor Americans wanted to stay out of the war, many felt that after WW1 they had dealt with enough war for their lifetime. This helped America during WW2 b/c we would ship and make a lot of weapons (and send supplies) for the allies. This was why there wasn't a depression for us after WW2. But when Pearl Harbor happened it devastated Americans into realizing they could no longer stay out of this war and therefore we went into war.