This goes way back...

Q: We recently returned from a trip to the U.S. Virgin Islands. Why did we have to go through Customs to board our return flight when we never left U.S. territory?

"What is seldom known is that the U.S. Virgin Islands is outside what is called 'Customs territory.' Since the acquisition of the Virgin Islands by the U.S. from Denmark [in 1916], by treaty, customs fees are assessed using local law.

When traveling to one of the U.S. insular possessions, such as the U.S. Virgin Islands, American Samoa or Guam, you are required to clear Customs and Border Protection and are entitled to a $1,600 duty-free exemption, as long as you are there for 48 hours or more."

The duty-free allotment of $1,600 in the Virgin Islands is twice as much as nearby Caribbean countries. In other words, you may want to pack an extra bag for tax-free purchases the next time you head to this tropical paradise.

No duty free when travelling from FL to NY.

Not sure how this affects the STT Covid testing policy.