In the past, Puerto Rico was an easy way into the U.S. from the Spanish Caribbean, particularly from the Domonican Republic. They would go to Puerto Rico, get a birth certificate for a dead Puerto Rican, then move on to the mainland U.S. There are several hundred thousand Dominicans in NYC alone.
Not the past — still going on today. They’re mostly in Washington Heights.
They should hire me at the boarding area at the airport — I can spot the Domincan 8 out of 10 times — spent some time there, and in PR.