The Indian Health Service (IHS) is an operating division (OPDIV) within the U.S. Department of Health and Human Services (HHS). IHS is responsible for providing direct medical and public health services to members of federally recognized Native American Tribes and Alaska Native people. IHS is the principal federal health care provider and health advocate for Indian people. The IHS provides health care in 37 states to approximately 2.2 million out of 3.7 million American Indians and Alaska Natives (AI/AN). As of April 2017, the IHS consisted of 26 hospitals, 59 health centers, and 32 health stations. Thirty-three urban Indian health projects supplement these facilities with a variety of health and referral services. Several tribes are actively involved in IHS program implementation. Many tribes also operate their own health systems independent of IHS. It also provides support to students pursuing medical education in order to staff Indian health programs. Formation and mission The provision of health services to members of federally recognized tribes grew out of the special government-to-government relationship between the federal government and Indian tribes. This relationship, established in 1787, is based on Article I, Section 8 of the Constitution, and has been given form and substance by numerous treaties, laws, Supreme Court decisions, and Executive Orders. Health services for the needs of American Indian and Alaska Natives in the United States were first provided through the Department of War from the early 19th century until the Office of Indian Affairs came into creation and took over the mission. After the mission again changed departmental authority to the Department of Health, Education, and Welfare's Public Health Service in 1955, the IHS was established. The original priorities were stated to be Assemble a competent health staff Institute extensive curative treatment for the seriously ill Develop a full-scale prevention program that would reduce the excessive amount of illness and early deaths, especially for preventable diseases Employment IHS employs approximately 2,650 nurses, 700 physicians, 700 pharmacists, 100 physician assistants and 300 dentists, as well as a variety of other health professionals such as nutritionists, registered medical-record administrators, therapists, community health representative aides, child health specialists, and environmental engineers and sanitarians. It is one of two federal agencies mandated to use Indian Preference in hiring. This law requires the agency to give preference to qualified Indian applicants before considering non-Indian candidates for employment, although exceptions apply. IHS draws a large number of its