Present your passport to proper customs agents in airports in the U.S. and foreign countries when traveling abroad. Passports are the only form of documentation accepted for international travel at U.S. or foreign airport.
Use your passport as your form of travel documentation when traveling to Mexico, Canada, the Caribbean and/or Bermuda on a cruise ship or by land. Alternative forms of documentation are valid when entering and returning from any of these countries by land or sea ports and your passport is not required, but it is accepted.
Provide proof of your identity to virtually anyone with your legal U.S. passport. For example, you can use your passport as photo identification when applying for a marriage license or traveling domestically in lieu of a driver's license or state-issued identification card.
