H.R. 9533, An Act to provide a civil government for Porto Rico (Jones-Shafroth Act), June 30, 1916
In addition to granting U.S. citizenship to Puerto Ricans, the Jones-Shafroth Act separated powers among the island’s three branches of government and established a bill of rights. With the outbreak of World War I, U.S. officials viewed Puerto Rico as vital to protecting the newly-opened Panama Canal. The act was viewed as a way to strengthen the bonds between the island and the mainland.
Records of the U.S. Senate, National Archives and Records Administration
Serving the Nation: Puerto Ricans
Puerto Ricans served with distinction in both world wars. About a month before the United States declared war on Germany in April 1917, President Woodrow Wilson signed the Jones-Shafroth Act, which granted Puerto Ricans U.S. citizenship. Two months later Congress enacted the Selective Service Act of 1917, eventually making all Puerto Rican men between the ages of 18 and 45 eligible for the draft. In total, approximately 20,000 Puerto Ricans served in World War I and 65,000 served in World War II.
We are conferring on them what they ought to have had years ago . . . the privilege of being American citizens and being placed under the protection of our flag.
Representative Horace M. Towner of Iowa, Speech to the U.S. House of Representatives, February 24, 1917