How did this go for you? Also seeing people on this forum mentioning American's don't need a PRTD, but I can find that anywhere on the IRCC website. Curious how it went for you.
My guess is you will never find a document that says US citizens do not need a PRTD.
Because the question is, need it for what exactly? The trick is that much of the time the 'enforcement' of PR card/PRTD requirement is put onto the airlines (or 'common carriers').
For PRs:
-most non-US nationalities need a PR card or PRTD to board a flight to Canada.
-any PR who is in USA can eg cross the border by foot and just identify themselves (much easier with a PR card or PRTD but not technically required).
-this is obviously easier for those that don't need visas to enter USA or already have them.
Yes, US citizen-PRs can just use their US passport to board a flight. Mostly this means they don't need PR cards or PRTDs. (But remember, US citizens can't be denied entry to USA, so they could all just fly to detroit or whatever and walk across anyway; it's more convenient but doesn't alter the fundamentals that much).
Covid: as I recall, it SEEMS there were a few cases where US citizens got caught in a catch-22 (of sorts) and couldn't board flights to Canada. "Normal" US citizens (not Canadian PRs) could mostly not travel to Canada (baord a plane) due to covid rules (or only with specific exemptions). US citizen-PRs could not be denied entry to Canada at a port of entry (or at least, on same basis as before covid).
BUT: it seems a few were treated as if these were entirely separate requirements, and denied boarding (and therefore could not get to a port of entry by plane to declare as PRs - although they could have flown to detroit and walked across).
I.e. if you want to board a plane as a PR of Canada, then you need a pR card or PRTD; if you want to board as a US citizen, you need to show you benefit from an exemption specifically for US citizens (essential workers and some others I think?). [I hope my phrasing of this makes sense to others.]
Now,
probably this was not intentional, jsut a lack of clarity about what to apply to US citizen-PRs during covid. It is, at any rate, now irrelevant.
So
probably we return to the pre-covid situation: US passport holders, whether PRs or not,
probably do not need PR cards or PRTDs.
But... what vaccionation rules etc apply, quarantine, etc., - I've stopped following. Check carefully. Use the arrivecan app. Ask your airline just in case - sometimes they themselves don't know.
And if you're a US citizen, well, worst case scenario (I think), you fly to detroit or seattle or whatever and find your way to a land border.