Win for TN nonimmigrant classification. TN nonimmigrant classification approved for Mexican citizen with an agricultural engineering degree. Client and his wife and child can now enter the United States and he can work for his employer, an organic farm in Southern California, for the next 3 years. The North American Free Trade Agreement (NAFTA) created special economic and trade relationships for the United States, Canada and Mexico. The TN category, a nonimmigrant classification, simply reflects this general exemption from the visa requirement. The TN status can be extended indefinitely in increments of up to three years. Permanent residents of Canada and Mexico are not able to apply for TN visas to work as NAFTA professionals.