No, U.S. citizens do not need a passport to travel to Puerto Rico because it is a United States territory. Traveling from the U.S. mainland to San Juan is considered a domestic flight, similar to flying between New York and Florida. In 2026, however, you must ensure your state-issued ID is REAL ID-compliant (indicated by a star in the upper right corner) to pass through TSA security, as the federal enforcement deadline has now passed. While you don't need a passport, many travelers in 2026 choose to carry one anyway as a definitive form of identification, especially if they plan to take a boat excursion that might enter international waters or visit nearby non-U.S. islands like the British Virgin Islands. For non-U.S. citizens, the same visa and passport requirements that apply to entering the United States mainland apply to Puerto Rico. It is also important to note that while no passport is needed, you will still encounter a "USDA Agricultural Inspection" for your luggage when returning to the mainland to prevent the spread of invasive species.