States with the largest Indian populations are Arizona, Oklahoma, California, New Mexico and North Carolina. Because the major concentrations of Indian tribal groups in the United States are located in the Southwest, more than half of the reported studies of cardiovascular disease and cardiovascular disease risk factors have been conducted in these groups. Studies have been reported in the Pima, Papago, Navajo, Apache, Hopi and other tribes in the Arizona and New Mexico region. In general, these studies have concluded that cardiovascular disease rates are lower in these Indian groups than in the United States population.