@El_Gato Not actually an exchange. :P: Puerto Rico is already a US territory and has been for a long time. They've actually had referendums a few times in the past about whether they wanted to remain a territory, become independent, or become a US state. They've just never had a strong enough push toward either of the extremes, so they've upheld the status quo.
@El_Gato Sorry, had to check Wikipedia. I knew Puerto Ricans got US citizenship, but I didn't know who qualified as Puerto Rican - if just being born there was enough. Looks like it is, says you're considered a Puerto Rican citizen if you were born there or if at least one of your parents was born there.