What evidence reveals the vital role that american manufacturing played in the victory of the allies?

Before the United States entered the war, Europe as at a stalemate with France overun by Nazi Germany and both Britain and Russia on the defensive.

After the United States entered, American Military weapons and vehicles were shipped to Russia, the UK and many other fronts.

It was due to American manufacturing that the Allies were able to muster large mechanized forces of tanks and artillery to repel German advances.

The arrival of the United States into the war completely changed the course of history