Which factor was the greatest advantage of the United States in world War two

The greatest advantage of United States in world war II was its ability to rapidly transition from peace to war and mass produce weapons and war equipment at a colossal scale. This was so effective that the USA was able to make up for time lost, and the nation was able to effectively train the necessary forces and then exert a massive material superiority.

The greatest advantage was that the United States joined the Second World War comparatively later than the other countries. Where Britain and France had already expended a great amount of their resources and faced great casualties (same with Germany which spent a great of deal of resources on Operation Barbarossa), the United States had been neutral and were able to pour huge finances into funding scientists to work on nuclear weaponry etc.