Meh. Don't get me wrong, the USA joining world war 1 was the final nail in the coffin and likely cut the war short by a lot (and made it a slam dunk for the allies, instead of a pyrrhic victory), but compared to, say, Canada or Australia (not to mention the UK and Russia that both lost as much, if not more men than France) they basically didn't fight. They joined very early and were invaluable in holding french territories throughout the war, which is why they both suffered more losses than the USA even though their militaries (and populations) were way smaller.

WW2 USA was an absolute juggernaut though