UPDATE - Dec 9, 2021
Travellers heading into the US by air will still require a negative Covid-10 test and be double vaccinated expect those with an exemption however instead of a 3 day window, the test now has to be no longer than a day. The type of accepted tests are still the same.

Fully vaccinated Canadians as of Nov 30 can now enter back into Canada without a negative PCR test so long as their trip is less than 72 hours. All passengers arriving from an international destination will require not only a negative test before departure but also will be tested at the Canadian airport they enter.

https://travel.gc.ca/travel-covid
https://www.cdc.gov/coronavirus/2019-...

With so many different forms, test and regulations, what should you know when travelling to/from Canada and the United States these days. These protocols on the video are from Oct 2021 and may change at anytime which is why I encourage you to check the links above to confirm.