Puerto Rico was ceded to the United States in 1898 by the Treaty of Paris as a result of the Spanish- American War. U.S. citizenship was granted to Puerto Ricans in 1917, and during World War II it became an important U.S. military base. On June 4, 1951, Puerto Ricans voted in approval of a law which allowed them to draft their own constitution, and on July 25 of the following year Puerto Rico was declared a Commonwealth of the United States. As a result, Puerto Ricans share most rights of other U.S. citizens, although they are not allowed to vote and for the most part do not pay taxes. Although several elections have been held since 1952 to reinstate Puerto Rico's commonwealth status, not all citizens are in agreement over it; over the years different factions have advocated independence for the island, sometimes resorting to violence. Since 1968, governmental...