Lighthalzen isn't really that american though, at least I think that the area (Schwartzwalt alone = the german Schwarzwald) has a little german flair, or at least shows the asian love for german words XD
I'm from europe, so maybe I'm not the right person to ask (hell I would love a german localized map, but this won't happen I guess XD), but when I'm thinking of the US, I'm mostly thinking of free and empty spaces next to the highways, sunny cities at the west and gothic cities on the east. Cowboys wouldn't came in my mind at first, cause I think this is some part of the past. I would more tend to a city in the style of the big cities of the east coast to be true.
But I can see that the western theme and the gunslinger are very popular, and they would fit as well. Western Steampunk would be cool. Mix the Cowboy style with steam machines. Also, don't forget the native americans if you go along with the western style. I guess in their mythologie you can find a whole bunch of cool "monsters" that would fit the theme. Maybe there could be a little native american camp on a fieldmap, or a little side city, and the quests could be about the "war" between both, that you have to end peacefully?
On the other hand I don't know if this topic is too sensible for some people... (I wouldn't like to hear idea's about a
-themed map as well, cause this is something we germans don't like to talk about
)