Passport valid for at least 60 days beyond period of stay required by all except:
1. nationals of the USA holding passport or other valid proof of identity (bearing a photograph), a valid onward or return ticket for stays of up to 30 days and proof of sufficient funds for the duration of stay.

Note: Under the Western Hemisphere Travel Initiative (introduced 23 January 2007), US citizens returning directly from a US territory do not need to present a passport to re-enter the USA. For further details about the Western Hemisphere Travel Initiative, visit the website of the US Department of State: http://travel.state.gov/travel/cbpmc/cbpmc_2223.html.

Pago Pago is not a port of entry to the USA and passengers proceeding to the USA must comply with the appropriate regulations.

All nationals must be in possession of a valid passport, documentation for onward travel, sufficient funds to cover their stay and a confirmed accommodation reservation. Advance hotel reservations are required in the absence of a local sponsor.

Depends on individual case. Advance permission must be obtained from the immigration authorities. Some nationals may be able to enter visa-free for 90 days or less.
2. in the EU, nationals of Bulgaria, Cyprus, Czech Republic, Estonia, Greece, Hungary, Latvia, Lithuania, Malta, Poland, Romania and Slovak Republic do need a visa.

Note: Nationals not referred to in the chart above are advised to contact the embassy to check visa requirements (see Contact Addresses in USA section).

US Consulate in plenty of time for prospective visits of more than 30 days (or consular section at US Embassy); see the USA section.