United States border entry rules tightened in the wake of the terrorist attacks of September 11, 2001. U.S. citizens, legal permanent residents, and visitors from other countries must present a valid passport or other approved travel document when crossing the U.S. border by air. Those crossing the U.S. border by land or sea typically are not required to present a passport, but must show documentation of some kind (depending on such factors as country of origin and immigration status).

This article highlights the basic border entry rules for those crossing into the U.S., including information for U.S. citizens; legal permanent residents ("green card" holders); citizens of Canada, Mexico, and Bermuda; visitors from other countries; and participants in the U.S. Customs and Border Protection's (CBP) Trusted Traveler Programs for low-risk visitors.

See "Crossing the Border" for more information and links to government resources and FindLaw articles.

U.S. Citizens

All U.S. citizens traveling by air (including children) are required to present a passport or some other kind of approved travel document in order to clear customs. In place of a passport, U.S. citizens may present a U.S. military ID with travel orders; a U.S. Merchant Mariner Document (when on official business); or a NEXUS card at airports with NEXUS kiosks.

NEXUS cards allow approved members with expedited travel (air, land and sea) between the U.S. and Canada. The Western Hemisphere Travel Initiative (WHTI)-compliant cards are part of the CBP's various Trusted Traveler Programs. CBP offers detailed information about the NEXUS card program, including a list of fees and step-by-step online application instructions.

U.S. citizens returning to the U.S. by land or sea must have documentation that complies with the WHTI, typically a passport or trusted traveler card.

Lawful Permanent Residents

As with U.S. citizens, lawful permanent residents (green card holders) also must present either a passport or secure travel document when entering the U.S. by air. When crossing the border by land or sea, LPRs may present their Permanent Resident Card (Form I-551).

See the CBP's "Entering the U.S. - Documents Required for Foreign Nationals" for more details.

Citizens of Canada, Mexico & Bermuda

Special rules apply to Canadian, Mexican and Bermudian citizens crossing the U.S. border as part of the WHTI. All international visitors (regardless of country of origin) must present a passport or secure travel document when entering the country by air. See CPB's interactive WHTI map for more detailed information.

• Canadian Citizens: Must present a single WHTI-compliant document when visiting by land or sea. Some Canadian citizens are subject to US-VISIT biometric procedures.
• Bermudian Citizens: Must present a single WHTI-compliant document when visiting by land or sea. All Bermudian citizens are subject to US-VISIT biometric procedures.
• Mexican Citizens: Must present a passport with a nonimmigrant visa or laser visa border crossing card when visiting by land or sea. Some Mexican citizens are subject to US-VISIT biometric procedures.

All Other International Visitors

International visitors to the U.S. typically must show a passport or e-Passport when going through customs.

Visitors from certain countries may enter the U.S. without a visa under the Visa Waiver Program and are subject to the Internet-based Electronic System for Travel Authorization (ESTA) prior to traveling to the U.S. Those entering the U.S. on a visa are subject to US-VISIT biometric screening procedures.

Trusted Traveler Programs

CBP's Trusted Traveler Programs encompass various types of pre-screenings to provide expedited travel through dedicated lanes for travelers determined to be low-risk.

• NEXUS: For approved members between the Canada and U.S. border for land, sea and air entry.
• SENTRI: For approved members between the Mexico and U.S. border for land, sea and air entry.
• FAST: For approved commercial truck drivers between the Canada and U.S. and Mexico and U.S. borders.
• Global Entry: For pre-screened international travelers to the U.S.

Get Your Questions About Crossing the Border Answered by a Legal Professional

Immigration laws are constantly in a state of flux. What was true yesterday under one president, may not be true under another. If you're concerned about how executive orders, changes in the laws, or any other matter might affect your ability to cross the border, you should speak with an experienced immigration lawyer near you.