Comment by gamblor956

You guys are talking about two similar and related but different things.

TN is both a "nonimmigrant classification" and a visa. The TN nonimmigrant classification is what is what grants a Canadian citizen eligibility to enter into the U.S. without a visa. A TN visa also grants a Canadian citizen entry into the U.S., and is required for TN nonimmigrants to enter with family members. In a nutshell, you establish your TN classification at your port of entry with (a) proof of Canadian citizenship, (b) letter from employer or prospective employer, and (c) any required credential and fees. You can acquire a TN visa the same way, or (recommended) at a U.S. consulate or embassy prior to your trip, and the primary difference is that the TN visa takes a little more time and paperwork.

Prior to this administration, TN status was a simple and short process; we had dozens of Canadian employees visiting the U.S. every week. However, the current administration does not believe in following established laws, so our legal counsel has been advising us to apply for TN visas for Canadian employees visiting the U.S prior to their trips to avoid any surprises at the border.

Note: Mexican citizens don't get TN nonimmigrant classification status. They must apply for the TN visa at a U.S. consulate or embassy in Mexico prior to their departure for the U.S. They must then apply for admission (aka, a visa) into the U.S. again when they actually arrive (basically, they need a TN visa to get a visa. It is as ridiculous as it sounds.)