They reached their goal in 1897; however, a year later, Spain ceded the island to the United States under the provisions of the 1898 Treaty of Paris, which ended the Spanish-American War. In 1917, Puerto Rico became a U.S. territory and its people became U.S. citizens.
Answer: It did not become a state, however it did become part of U.S territory. In 1917, Puerto Rico became a U.S. territory and its people became U.S citizens. So, it became part of the U.S in 1917.