Originally Posted by
catocony
Look, it's very simple - for a US citizen traveling to and from one of the 50 states, DC or Puerto Rico to the USVI, you do not need a passport. We're not discussing Guam or Samoa or Saipan or anything in the Pacific. So, the CBP was out of order in asking for a birth certificate for a baby on a flight from St. Croix to wherever the parents were flying to.
That a passport is not required does not mean they will not ask for ID.
The US State Department "suggests" you should carry ID and birth certtificate when traveling to PR & USVI.
I take this to mean that w/o these you will get in and back to the 50 states, but it might cause issues to not have them.