The USVI is made up of St. Thomas, St. John, St. Croix and 50+ smaller islands. While BVI has had a larger charter following over the years, more and more charter companies are operating bases out of the USVI.
Because USVI and BVI are so close, you can easily visit both island chains as part of an amazing bareboat charter vacation!
https://en.wikipedia.org/wiki/United_States_Virgin_Islands