What was the effect of the u. s entry into world war i?

1. No immediate military or economic impact on the war because the Allies had already relied on American industry to provide them with resources for the war.
2. Arrival of fresh American troops was the greatest contribution to the war. Boosted morale.
3. October 1918, America's effective army consisted of 4 million of which 2 million were placed in France and 1.3 million were fighting at the fronts.