Commonwealth Covenant Day is observed in the Northern Mariana Islands every March 24. This public holiday commemorates the anniversary of the enactment of the Covenant to Establish a Commonwealth of the Northern Mariana Islands in Political Union with the United States, which was approved by the US Congress in 1976. The Northern Mariana Islands, an inhabited US territory, decided to pursue commonwealth status rather than independence after a 1975 referendum where 79% of voters favored closer ties with the US. The islands have a complex history, having been colonized by the Spanish, then becoming part of the German Empire, and later administered by Japan before being invaded by the United States in 1944. Celebrations typically involve community events that reflect the islands' unique cultural heritage and their political relationship with the United States.