Answer: Some reasons why Puerto Ricans were given citizenship in 1917 include:
Campaign promise
Wilson campaigned on home rule for Puerto Rico and citizenship for Puerto Ricans in 1912.
Commercial advantage
Wilson recognized the commercial advantage of having better relations with Latin America.
Military need
Many have argued that the granting of American citizenship to Puerto Ricans was related to the need for soldiers as the U.S. entered the First World War.
Colonization
Puerto Rico is small and already well colonized by America.
Monroe Doctrine
Puerto Rico is part of the Americas and is covered under the Monroe Doctrine and the Roosevelt Corollary.