Apache Point Observatory is a private research observatory in Sunspot, high in New Mexico’s Sacramento Mountains, owned by the Astrophysical Research Consortium and operated by New Mexico State University. Formed in 1984 to build a 3.5-meter telescope, the consortium expanded beyond its founding universities as the site developed. Although construction began in 1985, problems with the primary mirror delayed full operations until November 1994. Its principal instruments include the ARC 3.5 m telescope, the SDSS 2.5 m telescope built for wide-field sky mapping, and smaller research telescopes. Since 2005, the site has also hosted lunar laser-ranging work and has contributed to discoveries of minor planets.