I just came across this map at the Pluralism Project. It's a geographical distribution of Islamic centers in the U.S. as of the Autumn of 2004. By the term "centers," I believe the researchers have included sites other than masjids (e.g., CAIR and MSA offices, and schools), plus the Ahmaddiya have been lumped in with the orthodox Muslims. If you click on the title link, you'll also find a number of similar maps for other non-Christian religions (e.g., Hinduism, Buddhism, etc.).