Autonomy and War
In 1897, in a desperate effort to hold on to its last two possessions in the Americas, Spain granted Cuba and Puerto Rico a broad array of rights including those under Title I of the Spanish Constitution, which bestowed all the rights of Spanish citizens and gave universal suffrage to all males more than twenty-five years old. Then on November 25, 1897, Spain approved the Carta Autonómica, also known as Constitución Autonómica, which gave Puerto Rico the right of self-government. The first elections under this new political arrangement were held in March 1898. At that time the Liberal Party, then led by Luis Muñoz Rivera, received most of the votes. However, tensions were already building between Spain and the United States, and Puerto Rico's short-lived experiment in self-government came to an abrupt end with the advent of the Spanish-American War.
In April 1898 the United States declared war on Spain and on July 25 U.S. troops invaded Puerto Rico in the course of the war's final campaign. Military operations on the island lasted approximately three weeks. October 18, 1898, when the last Spanish troops left Puerto Rico and the American flag floated atop most public buildings, marked the end of four centuries of Spanish Imperial occupation and the beginning of U.S. sovereignty at the dawn of what has been called the American Century.