Once a Japanese possession, the Northern Mariana Islands were occupied by the United States in 1944, and its administration used the US flag. In 1947 the islands became became part of the UN Trust Territory of the Pacific Islands and its administration used the flag of the United Nations till 1967, when the trust territory adopted the flag of their own.
The original flag of the Northern Mariana Islands was adopted by the district government on 31 March 1972, and by the territory government on 4 July 1976. The mwarmwar was added in 1981. In 1989 the shade of blue became darker.