As of June 1, 2009, all U.S. citizens are required to have a passport or a passport card for travel outside the United States, including land and sea travel to destinations such as Canada, Mexico, and the Caribbean. This requirement applies to all forms of travel, not just air travel. The only exception is for children under the age of 16, who may still be allowed reentry from Canada, Mexico, or the Caribbean with a birth certificate or naturalization paper. Additionally, there is mention of the option to obtain a passport card, which is a more affordable alternative to a passport book. The information provided suggests that you can apply for a passport card by mail. For the most up-to-date information on passport requirements and to find a passport processing center near you, it is recommended to visit the official website mentioned or contact the U.S. Department of State. Keep in mind that passport regulations may have changed since my last knowledge update in January 2022, so verifying the current requirements is crucial.– iafdb.travel.state.gov