Natural disasters , including a major earthquake and tsunami in 1918 and several hurricanes , as well as the Great Depression , impoverished the island during the first few decades under U.S. rule . Some political leaders , such as Pedro Albizu Campos , who led the Puerto Rican Nationalist Party , demanded a change in relations with the United States . He organized a protest at the University of Puerto Rico in 1935 , in which four were killed by police
earthquake
1918 San Fermín earthquake
Puerto Rico