But someone should help me with this faction, I don't have a good idea about them.
america's strong point in ww2 on the western front was their air superiority, and artillery. the problem is strafing runs and arty barrages (either call in, or buildable howizer) is it doesn't reflect it's actual power during the war. if you see the red flares, you retreat your units. if you see an arty shell land near your trrops, you retreat them. if you see a plane strafe your units, you retreat.
when in actuality, if you get barraged by arty: you cower and hide, run for the nearest cover, and hope to god none of the shells land nearby. if a plane flies overhead and starts strafing, or dropping bombs. you just hope that your foxhole is deep enough, or the pilot can't aim.
everything they had else was pretty mediocre. they were fighting a weakened nation. desperate german soldiers battleweary from years of fighting in france and on the eastern front. their tanks wern't as advanced as the germans, but they had a lot of them. Their infantry wern't as experienced. but they were numerous. their logistics system was amazing, but you can't really show that in COH2.
so USF is weird. relic's just decided to make them a "jack of all trades, master of none" early-game orientated, map control dependant. infantry reliant faction.