On July 25, 1898 at the outbreak of the Spanish–American War, Puerto Rico, being a colony of Spain, was invaded by the United States of America with a landing at Guánica. Spain was forced to cede Puerto Rico, along with Cuba and the Philippines, to the United States under the Treaty of Paris (1898). The twentieth century began under the military regime of the United States with officials, including the governor, appointed by the President of the United States. In 1917, the Jones-Shafroth Act approved by the United States Congress granted Puerto Ricans U.S. citizenship so that they could be recruited as soldiers for WWI. Natural disasters and the Great Depression impoverished the island. Some political leaders demanded change; some, like Pedro Albizu Campos, would lead a nationalist (The Puerto Rican Nationalist Party) movement in favor of independence. He would eventually die by what he claimed was a conspiracy set in place by the U.S. Federal Government. Muñoz Marín initially favored independence, but saw a severe decline of the Puerto Rican economy, as well as growing violence and uprisings, at the hands of the U.S. government and opted to create the "commonwealth" option as an eventual stepping stone to full independence.
Change in the nature of governance of the island came about during the later years of the Roosevelt–Truman administrations, as a form of compromise spearheaded by Luis Muñoz Marín and others, and which culminated with the appointment by President Harry S. Truman in 1946 of the first Puerto Rican-born governor, Jesus T. Piñero. In 1947, the United States granted the right to democratically elect the governor of Puerto Rico. Luis Muñoz Marín would become the first elected governor of Puerto Rico in the 1948 general elections.
Starting at this time, there was heavy migration from Puerto Rico to the continental U.S.A. in search of better economic conditions. In 1945 there were 13,000 Puerto Ricans living in New York City - by 1955 there were 700,000, and by the mid-1960s there were over a million.
On November 1, 1950, Puerto Rican nationalists Griselio Torresola and Oscar Collazo attempted to assassinate President Harry S. Truman. Subsequently, Truman allowed for a genuinely democratic referendum in Puerto Rico to determine whether Puerto Ricans desired to draft their own constitution.
Puerto Rico adopted its own constitution in 1952 which adopted the name "commonwealth" for the body politic and which is used by many as the name of Puerto Rico's current relationship with the United States. During the 1950s Puerto Rico experienced a rapid industrialization, with such projects as Operation Bootstrap which aimed to industrialize Puerto Rico's economy from agriculture-based into manufacturing-based.
Present-day Puerto Rico has become a major tourist destination and a leading pharmaceutical and manufacturing center. Still, Puerto Rico continues to struggle to define its political status. Three locally-authorized plebiscites have been held in recent decades to decide whether Puerto Rico should request independence, enhanced commonwealth status, or statehood. Narrow victories by commonwealth supporters over statehood advocates have not yielded substantial changes in the relationship between the island and the United States. In the latest status referendum of 1998, commonwealth status won over statehood with 50.2% of the votes, and support for the pro-statehood party and the pro-commonwealth party is about equal. The only major independence party on the island, the Partido Independentista Puertorriqueňo or PIP, usually receives 5-6% of the votes in the elections though there are several smaller independence groups like the Macheteros. On December 22, 2005, a task force created by President Clinton and appointed by President George W. Bush called on Congress to hold the first federally-authorized vote ever for Puerto Rican voters to decide whether they wished to continue their current relationship, described as an unincorporated territory subject to the will of Congress, or whether they wish to choose in a subsequent vote among permanent non-territorial options, which the report enumerates as statehood or independence. The Legislature, as well as the political parties, were gearing up in early 2006 to lobby Congress to address the Presidential task force recommendations.