Spanish-American War: A conflict between Spain and the United States in 1898, resulting in American acquisition of territories including Puerto Rico, Guam, and the Philippines.
Foraker Act: Passed by Congress in 1900 to establish a civil government for Puerto Rico. It also officially designated Puerto Rico as an "unincorporated territory" of the United States.
Jones Act: A law passed in 1917 granting U.S. citizenship to residents of Puerto Rico while maintaining its status as an unincorporated territory.