Some independent bookstores in your area might carry American fiction. Check out the ones in your neighborhood or downtown area. Also, you can search online for bookstores near you and see if they have what you're looking for.
You might have luck at a large bookstore chain like Barnes & Noble. They usually have a wide range of American fiction titles. Another option is to look for second-hand bookstores, as they sometimes have hidden gems of American literature.
You could try your local library. They often have a good selection of American fiction.