Puerto Rico has been under U.S. sovereignty for over a century when it was ceded to the U.S. by Spain following the end of the Spanish–American War, and Puerto Ricans have been U.S. citizens since 1917. The island's ultimate status has not been determined as of 2012[update], its residents do not have voting representation in their federal government. Puerto Rico has limited representation in the U.S. Congress in the form of a Resident Commissioner, a delegate with limited no voting rights. Like the states, Puerto Rico has self-rule, a republican form of government organized pursuant to a constitution adopted by its people, and a bill of rights.
Try to answer this question if possible (otherwise reply "unanswerable"): How long have Puerto Ricans been U.S. citizens?
since 1917