On March 2, 1917, President Woodrow Wilson signed the Jones-Shafroth Act. This law gave Puerto Ricans U.S. citizenship. The Jones Act separated the Executive, Judicial, and Legislative branches of Puerto Rican government, provided civil rights to the individual, and created a locally elected bicameral legislature. The two houses were a Senate consisting of 19 members and a 39-member House of Representatives. However, the Governor and the President of the United States had the power to veto any law passed by the legislature. Also, the United States Congress had the power to stop any action taken by the legislature in Puerto Rico. The U.S. maintained control over fiscal and economic matters and exercised authority over mail services, immigration, defense and other basic governmental matters.

Ref: Jones-Shafroth Act - The Library of Congress