[Maciek416]

I am not a lawyer. The transition from TN->GC is possible too under the right (narrow) circumstances. The big tradeoff is not risking travel while within the lifecycle of one TN term, and likely not being able to straddle a GC application across the boundaries of a TN renewal period at all. For some countries of birth, a TN term is not long enough to get through the GC pipeline. But for Canadians born in Canada, ones who have family willing to visit them instead of the other way around, it may be doable. Or for folks born in other countries which have no GC backlog or a short one. YMMV, but I have personally seen someone go L2->TN->GC. An unusual sequence but necessary given the particulars of that case.

[ashconnor]

It's totally possible to go from TN to GC but you won't be able to leave the United States from the point you file your I140/I485 until your Advanced Parole document turns up. You also can't get a new TN should you need one.

[Scoundreller]

> you won't be able to leave the United States from the point you file your I140/I485 until your Advanced Parole document turns up

How long does this take usually?

[ashconnor]

8-18 months according to the USCIS website.

I also forgot to mention that you have to wait 91 days from your last entry before filing the I485 to bypass the single-intention of TN.