From my point of view the American Girls are girls personalities that a guirl buy as a doll. Are toys in which girls seing a "18-inch plastic doll, made by the Pleasant Company and marketed under the optimistic brand name American Girl" with diferent special characteristics depending on the style, a girl could see their life and personality reprecented on a doll.
Also I belive that the American Girls (dolls) is, was and will still be a big and amazing U.S adictive marketing campaig in which girls will continue buying dolls.
To conclude, I personally belive that business on U.S is too big and will grow with the pass of time, as American Girls. The Author of American Girls sold the company to Mattel in 770 millon u$$, we can see that U.S business is big and will still grow!