The first American passports were issued to a select number of citizens of the thirteen states during the War for Independence in the 18th century. Based on a French design, they were single sheets of paper with a description of the bearer, and valid from three to six months. Today 30 percent of U.S. citizens have passports – around 90 million – and a further three million have passport cards. Nowadays, there are just a few options to consider if traveling without a passport.

Head to the U.S. Territories

No passport is required to travel to U.S. territories, whether by air, land or sea. Instead, travelers must carry valid photo identification, such as a current driver's license or ID card, which can be issued to non-drivers by their state’s motor vehicles department. These territories include American Samoa, Baker Island, Howland Island, Guam, Jarvis Island, Johnston Atoll, Kingman Reef, Midway Islands, Navassa Island, Northern Mariana Islands, Palau, Palmyra Atoll, Puerto Rico, US Virgin Islands (St. Croix, St. John and St. Thomas) and Wake Island.

By Land or Sea

Americans visiting Mexico, Canada, Bermuda and the Caribbean by land or sea can travel using a passport card or enhanced driver's license. Pre-approved travelers can also enter the U.S. with the Trusted Traveler Program Nexus card. Children younger than 16 – or 19 when traveling with specific cultural or sports groups – are permitted to use a copy of their birth certificate or naturalization certificate. Members of the military can go with their identification card, while Native Americans can present tribal documents. There are other exemptions, covering those vacationing on cruises returning to the same U.S. port, Lawful Permanent Residents and passengers of small boats.

In the Air

Those wishing to visit Canada can use a Nexus card, which is part of the Trusted Traveler Program. The card is a joint American and Canadian initiative to let pre-approved, low-risk travelers cross the border swiftly. When traveling to any other foreign nation by air, U.S citizens must have a passport. The rules changed in 2007 when the Department for Homeland Security ended the right of Americans to travel between Mexico, Canada, the Caribbean, Bermuda and Panama, bearing only proof of U.S. citizenship, such as an approved birth certificate or driver's license.

Passport Card

The passport card, which was previously known as the People Access Security Service (PASS) card, is a more convenient, and less expensive, alternative to the passport book. Introduced by the Western Hemisphere Travel Initiative in 2009, the wallet-sized card is for U.S. citizens only and can be used to re-enter the United States from Canada, Mexico, the Caribbean, and Bermuda at land border crossings or sea ports-of-entry.