How did America win WWII?

Question:

I know allies played a major role, but what did America do to help win the war. More than one example please

Answer:

1. Defeated Japan (the Pacific Theater is something that only the United States can say it won, they were the only country with enough people to contribute enough troops to fight the Japanese almost alone.)
2. They contributed thousands of troops to the European Theater, including those that fought alongside the British and Canadians at Normandy.
3. Even before joining the war, the United States was selling and later giving war equipment to the United Kingdom, the Soviet Union, and all of the other allies. The war gave many people in the United States jobs in factories and in the army after the Great Depression.