Citizenship Day is observed in the Northern Mariana Islands every November 4. Established in 1986, this official public holiday commemorates the day when United States citizenship was conferred on legally qualified residents of the Commonwealth. The Northern Mariana Islands, part of the Mariana Islands archipelago in the northwestern Pacific Ocean, became a United States commonwealth in 1976 following a status referendum, although the islanders did not gain U.S. citizenship until a decade later. The holiday serves as a celebration of this significant milestone in the islands' history, which includes a complex colonial past involving Spain, Germany, and Japan before U.S. administration.