Kia ora Silke
On July 25, 1898 at the outbreak of the Spanish–American War, Puerto Rico was invaded by the United States with a landing at Guánica. Following the outcome of the war, Spain was forced to cede Puerto Rico, along with Cuba, the Philippines, and Guam to the United States under the Treaty of Paris (1898). Puerto Rico began the twentieth century under the military rule of the United States with officials, including the governor, appointed by the President of the United States. The Foraker Act of 1900 had given Puerto Rico a certain amount of popular government. By 1917, the Jones-Shafroth Act granted U.S. citizenship to Puerto Ricans - a status they still hold today. Many Puerto Ricans served in the U.S. Armed Forces beginning in World War I. 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 served many years in prison for seditious conspiracy to overthrow the U.S. Government in Puerto Rico. Luis Muñoz Marín initially favored independence, but saw a severe decline of the Puerto Rican economy, as well as growing violence and uprisings and opted to support the "commonwealth" option instead. The "commonwealth" was supported before Luis Muñoz Marín by other political leaders.
Change in the nature of the internal governance of the island came about during the later years of the Roosevelt–Truman administrations, as a form of compromise spearheaded by Muñoz Marín and others, and which culminated with the appointment by President Harry 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 became the first elected governor of Puerto Rico in the 1948 general elections, serving as such for 16 years, until 1964.
Starting at this time, there was heavy migration from Puerto Rico to the Continental United States, particularly New York City, in search of better economic conditions. Puerto Rican migration to New York averaged as follows: 1930-1940, 1,800; 1946-1950, 31,000; 1951-1960, 45,000, 1953 (peak year), 75,000. As of 2003, the U.S. Census Bureau estimates that there are more people of Puerto Rican birth or ancestry living in the United States than in Puerto Rico itself.