The main population center of the reservation is centered around Cataract Canyon (also known as Havasu Canyon), where the capital of the reservation, Supai, is located. Supai has been referred to as "the most remote community" in the contiguous United States by the U.S. Department of Agriculture. It is accessible only by helicopter, on foot or by mule. Supai is from the nearest road and has no automobiles in the community. It is the only place in the United States where mail is still carried out by mules.