Automatic visa revalidation is one of a handful of exceptions to the general rule that a person who is not a United States citizen or lawful permanent resident can only lawfully enter the United States if he/she has a valid visa. According to automatic visa revalidation, people on some non-immigrant visa statuses who visit Canada, Mexico or some adjacent islands close to the United States for a period of less than 30 days can re-enter the United States based on a valid Form I-94 even if their visa has expired.[1][2][3]