I come from Denmark, but live in SF holding a B visa. I am planning a trip to Puerto Rico and want to make sure I have enough time to catch my connecting flight on the way home. My route home is either PR - Atlanta - SF or PR - JFK - SF. I have already entered the US on my first arrival to SF, so now I wonder if I have to go through immigration again when returning from PR?
There is no immigration on flights between Puerto Rico and the US mainland.
Upon arrival in Puerto Rico there are some level of agricultural checks that people may equate to customs, but there is no immigration.