I'm getting mixed info about passport requirements for travel between Main land US and USVI. I was told that we do not need a passport, but other have said we do. I looked for info on the goverment website and gave up. Can anyone point me to an official website that has this information? We'll be flying from NYC direct to St Thomas, and returning via Puerto Rico.

You do not have to have a passport to travel to the US Virgin Islands, nor do you have to have a passport for Puerto Rico, which is considered a domestic US flight.

I'm puzzled why you can't easily find this information since it's been the cornerstone of the USVI tourism campaign for the past 5 years. Here's a link: http://www.usvitourism.vi/frequently_asked_questions

However, you must be prepared to show proof of citizenship to fly back to the US from the USVI (or on to Puerto Rico), so you will require a government-issued photo ID plus an original copy of your birth certificate with raised seal.

Though perhaps you want something more "official". Here's a link to the web site of the department of state:
http://travel.state.gov/travel/cbpmc/cbpmc_2223.html

The US Virgin Islands are a U.S. territory.

http://www.usvi.net/us-ins/

I'm going to ditto that comment about needing proof of citizenship for everyone including infants. I fortunately threw in my daughter's birth certificate at the last minute forgetting that we might need something official since we weren't bringing our own passports (and we've never had it checked when flying domestically).

The State Department and the USVI tourist bureau have really furthered the confusion on this issue in the past couple of years. I travel to the USVI every year, and always carry my passport, which they always ask for. Yes, technically you don't need a passport, but you do need proof of citizenship. The real problem is that I can't find anything on the State Department pages that actually explain this - they just say that a passport is not needed (thanks for the link to the INS page on usvi.net - it is the first time that I've actually seen it spelled out, and I've been looking!). The problem is compounded because the flight TO the USVI is a domestic flight, so no one checks to see that you are carrying the documents that you will need to actually get on the flight back to the mainland. "Passports" are always the first thing on our packing check list when we visit St. Croix.