On July 25, 1898, during the Spanish -- American War, the U.S. invaded Puerto Rico with a landing at Guánica. As an outcome of the war, Spain ceded Puerto Rico, along with the Philippines and Guam, then under Spanish sovereignty, to the U.S. under the Treaty of Paris, which went into effect on April 11, 1899. Spain relinquished sovereignty over Cuba, but did not cede it to the U.S.
since when is puerto rico part of the us
April 11, 1899