U.S. Territories By 4thgradeclass Period: Jan 1, 1898 to Jan 1, 2000 1898 to 2000 Dec 10, 1898 Guam becomes a U S territory Apr 2, 1900 Puerto Rico becomes a U S territory Apr 17, 1900 American Samoa becomes a U S terriotry Mar 31, 1917 U.S. Virgin Islands becomes a U S territory