[wenc]

For Canadians, TN-1's are not visas but statuses adjudicated at the border (they're typically just I-94s linked to passports), so they never "run out" as such (no quota).

However the TN is a status for restricted NAFTA (USMCA) professional categories, and typically requires proof of qualifications (in this case, education). I could be wrong, but an undergrad intern typically does not fit these categories. I'm surprised people have used it for co-op.

[ska]

Right, that's why I put visa in quotes. And yes, there is no quota but I wasn't clear if there were e.g. COVID related restrictions on application currently.

People have definitely used this for even undergrad co-op, but I don't know how widespread. Obviously more easily applicable for grad students.

Part of the issue is that as you note the admissibility criteria is decided by the border agent you randomly see. So you provide evidence of education and fit for a TN category, but they decide if you qualify, and it's unclear how much guidance they have in this. Appeal process is mostly only through the same agent.

NB: my experience in this area is a bit out of date, things may have changed.