American Samoa, unincorporated territory of the United States, formed by a group of seven islands in the southern Pacific Ocean, comprising Tutuila, on which a US naval station is located; the Manua group, consisting of Tau, Olosega, and Ofu; Aunuu; Rose Island; and Swains Island. Privately owned Swains Island and uninhabited Rose Island are coral atolls; the other islands are mountainous and of volcanic formation. Tutuila is the largest island of the group, covering an area of about 143 sq km (55 sq mi) and with a 1990 population, including Aunuu, of 45,043. Pago Pago, on Tutuila (1990 population, 3,519), is the seat of government of American Samoa and has one of the finest harbours in the South Pacific. Area: 200 sq km (77 sq mi); in early 1990 the population was 46,773.