All people entering American Samoa must pass through American Samoa Immigration and Customs. Passports are necessary not only to enter American Samoa and re-enter the U.S., but are now required for check-in on the airplane as well. Flights to American Samoa are considered International. Citizens of other nations must have passports to enter American Samoa. Everyone must possess a ticket for return or onward passage.
U.S. citizens returning from American Samoa are permitted a duty free allowance of US$800 rather than the usual US$400 if it all originated in American Samoa. (See the U.S. Customs web page)