Guam ( GWAHM; Chamorro: Guåhan [ˈɡʷɑhɑn]) is an island that is an organized, unincorporated territory of the United States in the Micronesia subregion of the western Pacific Ocean. Guam's capital is Hagåtña, and the most populous village is Dededo. It is the westernmost point and territory of the United States, as measured from the geographic center of the U.S. In Oceania, Guam is the largest and southernmost of the Mariana Islands and the largest island in Micronesia. In 2022, its population was 168,801. Chamorros are its largest ethnic group, but a minority on the multiethnic island. The territory spans 210 square miles (540 km; 130,000 acres) and has a population density of 775 per square mile (299/km).
Indigenous Guamanians are the Chamorro, who are related to the Austronesian peoples of the Malay Archipelago, the Philippines, Taiwan, and Polynesia. Unlike most of its neighbors, the Chamorro language is not classified as a Micronesian or Polynesian language. Like Palauan, it possibly constitutes an independent branch of the Malayo-Polynesian language family. The Chamorro people settled Guam and the Mariana islands approximately 3,500 years ago. Portuguese explorer Ferdinand Magellan, while in the service of Spain, was the first European to visit and claim the island in March 1521. Guam was fully colonized by Spain in 1668. Between the 17th and 19th centuries, Guam was an important stopover for Spanish Manila galleons. During the Spanish–American War, the United States captured Guam in June 1898. Under the 1898 Treaty of Paris, Spain ceded Guam to the U.S. effective April 11, 1899.