The Chilocco School closed on June 3, 1980 when the U.S. Congress ceased funding. In the school's 1980 yearbook, Superintendent C. C. Tillman wrote, "Chilocco is another in a long list of broken promises." During its history nearly 18,000 students from 126 Indian tribes attended Chilocco. Chilocco granted high school diplomas to 5,542 students. Graduates included 688
Cherokees, 573
Choctaw, 545
Navajo, and 452
Creek divided between 2,741 females and 2,801 males. After closure, the school's land was granted to five local tribes as the Chilocco Development Authority; the
Kaw Nation (.10 mineral interest), the
Otoe-Missouria Tribe (.10 mineral interest), the
Pawnee Nation (.10 mineral interest), the
Ponca Nation (.10 mineral interest), and the
Tonkawa Tribe (.10 mineral interest). The
Cherokee Nation holds a .50 mineral interest. Between 1989 and 2001, the property was leased to
Narconon, which operated a substance abuse rehabilitation center at the site. In 2000, the Council of Confederate Chilocco Tribes was created by the Chilocco Treaty between the United States and the
Kaw Nation,
Otoe-Missouria Tribe,
Pawnee Nation,
Ponca Nation, and the
Tonkawa Tribe. The treaty gave these nations joint authority to oversee and manage the former campus. In 2011, Chilocco was closed to the public and used as a training and practice facility for
federal law enforcement personnel. In November 2017, the
Department of Homeland Security published a statement in
The Newkirk Herald warning local residents it was conducting tests at Chilocco Indian School. The statement advised "in January/February and again in June/July 2018, particles will be released onto buildings of the Chilocco campus. It is to determine how well biological agents will penetrate into single and multi-family homes." The department stated these chemicals are nontoxic and nonhazardous, but many in the community of
Newkirk, Oklahoma expressed skepticism. The Department of Homeland Security report on the test confirms the chemicals used were nontoxic. Permission to use Chilocco as the site of their test was granted by the Council of Confederate Chiloco Tribes. In 2021, after the discovery of hundreds of graves at
Canadian residential schools the Chilocco Alumni Association called for ground penetrating radar equipment to survey outside of the cemetery for unmarked graves. ==Notable alumni==