Being on a government watchlist, such as the U.S. Terrorist Screening Database, primarily affects your ability to travel and interact with border authorities. The most restrictive subset is the "No Fly List," which prevents individuals from boarding any commercial aircraft flying into, out of, or within the United States. However, most people on the broader watchlist are still permitted to fly but are flagged for "Secondary Security Screening Selection" (SSSS). If you see "SSSS" on your boarding pass, you will undergo a much more intensive physical search, including a full-body pat-down, detailed luggage inspection, and swabs for explosives. This process can add significant time to your airport experience. Beyond the airport, watchlist status may lead to delays at land borders and increased scrutiny during interactions with law enforcement. In 2026, many travelers with similar names to those on watchlists use a Redress Number through programs like DHS TRIP to resolve cases of mistaken identity and avoid these persistent "false positive" delays.