There are many ideas and thoughts as to what constitues "American" Karate. Ultimately, Karate is a Japanese discipline, so there is really no true American Karate.

Most American Karate schools teach a blend of styles. The senior instructor, or leader of the parent organization, often train in several styles of marital arts. Taking from each system the techniques and philosophies that they like or understand, they develop their own style.

While ultimately there is nothing wrong with this practice, the important thing to remember is that the creator of the system developed it to fit themselves. The techniques used were chosen because they work with their capabilities, strengths, weaknesses and body type. As discussed before, when considering any martial arts school, make sure to understand the philosophies of the style along with the emphasized techniques.