When did citizens in Puerto Rico receive United States citizenship?

The citizens of Puerto Rico were granted U.S. citizenship on March 2, 1917. On this day in 1917, President Woodrow Wilson signed the Jones-Shafroth Act, more commonly known as the Jones Act. It was this act which made residents of Puerto Rico, a Spanish speaking U.S. possession, American citizens.

When the act was passed, Puerto Ricans were granted statutory citizenship, meaning that citizenship was granted by an act of Congress and not by the U.S. Constitution (thus the action was not guaranteed by the U.S. Constitution). Notwithstanding this fact, most Americans were and are happy that these actions were finally taken.

Residents of the island who were granted citizenship were allowed to reject it. They could voluntarily refuse within the first six months after the act was implemented. With almost 1.2 million residents on the island, only 288 rejected it by the end of the year (1917).