The North American Free Trade Agreement (NAFTA) created special economic and trade relationships for the United States, Canada, and Mexico. Under this NAFTA agreement, these three countries also established a category for professionals in certain fields to seek temporary entry into the United States to engage in business activities. This category is known as the Treaty NAFTA or just TN. The TN status or TN Visa is a special non-immigrant work status in the United States for a citizen of Canada and Mexico.
According to the U.S. Citizenship and Immigration Services, you may be eligible for TN nonimmigrant status, if:
You are a citizen of Canada or Mexico;
Your profession qualifies under the regulations;
The position in the United States requires a NAFTA professional;
You have a prearranged full-time or part-time job with a U.S. employer (but not self-employment - see documentation required below); and
You have the qualifications to practice in the profession in question.