Since the USVI are US territories, is clearance through customs/immigration still required at the first point of entry?

I wondered the same thing. We went through customs/immigration even though we never left St. John. Think everyone flying from St. Thomas goes through customs/immmigration there since it's a US point of entry.

We went through customs/immigration at the airport in St. Thomas after a week there. It is a US territory but since it's a "port of entry" you have to do customs.

You will go through Customs and Immigration upon your return to the mainland from the USVI, not upon your arrival to the USVI from the mainland.
You will also go through immigration if you make a trip to the BVI.
Hope that helps!
Mermaid

nibblette: You will go through customs/immigration at the airport in St. Thomas on your way BACK TO the U.S. mainland. Same thing if you're staying in St. John since you get there via St. Thomas.
I don't know how it works for St. Croix since I haven't been there. Since they have an airport, I presume they have customs/immigration? Does anyone know?

Give yourself plenty of time if returning from St. Thomas. The imm/customs line there was atrocious, and I'm told it's always that way.

You do go through Customs when you leave St. Croix, also.

When returning to the US Mainland from the USVI you go through customs at the departing airport. That would most likely be St. Thomas or St. Croix. There is no customs at the arriving airport in this case, since you are already in the US. Since the USVI is an easy point of entry for people trying to get into the country illegally, even US citizens must go through customs to prove their identity. I've heard STT can have long lines, but last time I was through on a weekday, the volume was light. Plan for lines though, in case it's busy on your day.