United States Overview
The US focus on offence, as most units are equipped to deal damage fast enough before something is able to kill them. Many, many tactics can be employed by the US, as they have a lot of options by midgame and switching tech doesn't seem to throw US back all that much.
While offence is good, there are times when you need to protect yourself from invading forces. Unfortunatly, US don't really defend all that well. Often a defending US player will retreat to get more breathing room, while other factions can hold any sort of ground comfortably. Shorter ranged units have this behaviour in general.
While US have a solid midgame and a very aggresive start with powerful infantry and much better Shermans, they lose a lot of that momentum once other factions get to catch up in the tech tree, making Shermans not too good in general.
US infantry has less range then others, but compensates by dealing much more damage. In general, US infantry are superior to most, as they make fights very short. The rifle squads also get 2 light machine guns to level the field even more.
The general idea retains with even the HMG's, though, making the US be alonside germany for worst machine gun nests in the game.
Probably ignoring anything orthodox in the menu, the US AA truck will be made in almost every game. The reason is not that aircraft is a counter to the US, but the AA truck can munch up infantry faster then heavy machine guns. When things get really rough, you might want to chose dedicated anti infantry support units like the scott, which is more like a downward facing mortar.
The greyhound serves as an early anti armor solution. Somewhat slow an clumsy, it can be out manuevered and that's often the case. However, a hit from the greyhound is not something the enemy will just shrug off.
The US get's some toys in the tank department, as well as a lot of different shermans. First of is the only shotgun in the game - the stuart light tank. Noisy and ineffiecient, the stuart focuses on removing excess infantry from the field. The second toy is the wolverine. Probably one of the cheapest anti-tank solutions in the game, the wolverine is often made in bulk and can deal with most medium tanks without encountering difficulty.
Hope you like Shermans, because they are the mediums and heavies of the US. Fortunatly, unlike real shermans, these don't randomly break on the field, but they get to keep their low cost. Shermans can be decribed as above average, but they still get a hard time when more competent advanced mediums show up. This is rearely a problem, as even the more advanced versions of the serman are relativly cheap.
US aircraft is slightly below aaverage in most aspects, but surpasses everyone when it come to the paradrop. Loud and freightning, it flies over any land AA, able to drop a rather lrge squad of infantry anywere on the field. The infantry itself can't survive the AA fire though, and the carrier can be intercepted by aircraft.
A US player shouldn't worry about enemy aircraft all that much, hovever, since all Shermans and Sherman-based tanks have their own AA weapons, as well as planty mobile AA trucks present at any given time.
US artilley is above average in preformance, but nothing too special to note. The US AT guns are powerful in theory, but in practice they are innacurate. US generally don't make artillery, as using massed Shermans is much easier and more adaptable.