Depends on what you mean by American style. Authors from America employ an endless variety of styles (for example, Fitzgerald and Hemmingway are almost opposites, yet both regarded as great American writers). I think your time would be better spent learning about style and voice in general, as opposed to trying to find a particularly "American" style.
If you want dialogue, then it's best to live in the country if you can. If not, then try to read some modern authors, particularly with teenage characters
In short, read some American books, magazines and newspapers