Passenger Vessel Services Act of 1886 (PVSA)
Any passenger vessel whose itinerary starts and ends at a US port without visiting a foreign port must be USA-made and have a USA crew.
Norwegian Cruise Line's Pride of America is the only cruise ship with an all USA crew as it is stationed full-time in Hawaii and does not have any way to visit a foreign port on its Hawaii-exclusive itineraries
The Exceptions and Workarounds
A passenger vessel visiting a US port may be foreign-made and/or have a foreign crew when...
Itinerary is roundtrip to/from the same US port
Itinerary starts and ends at different US ports
Coastwise penalty is $778/passenger
Source: US Customs and Border Protection