Puerto Rico was annexed by the United States in the aftermath of the Spanish-American War of 1898. Puerto Ricans are not, strictly speaking, immigrants. Few Puerto Ricans migrated to the United States after World War II. There was extreme poverty in Puerto Rico. The postwar developed cheap airline fairs between Puerto Rico and the United States, about 50 dollars, two weeks' wages. Cheap fares enabled 10's of thousands of Puerto Ricans to come annually.
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