The North American Free Trade Agreement (NAFTA) established a TN (Trade NAFTA) visa classification which is restricted to citizens of Canada and Mexico.
TN status is limited to certain professions stipulated under NAFTA and may be granted in up to 3-year increments. There is no limit to the number of years an individual may hold TN status, but the employment must be temporary in nature. TN visa classification is not to be used for tenured or tenure-track faculty or for permanent staff positions. Like the H-1B, the TN visa is employer and position specific.