I believe this is the current restriction order. Allows US citizens to travel through specific border crossings into BC and Alberta, if en route to Alaska...but with a lot of restrictions. Basically must drive straight through with limited stopping for fuel, overnight, eating, etc. No tourist stops, no provincial or national park visits, etc. You should check first though if there's a further update when you do leave.
When you drive through Fort St John BC on the Alaska Hwy on your way up and if you see a good lookin' gal with long brown hair with her good lookin' Canadian Vet husband and their gorgeous little 15 month old daughter in a new White Chevy PU, please wave and say hi for me.... haven't seen our granddaughter and her parents in person since June :'(
https://www.canada.ca/en/border-services-agency/news/2020/07/covid-19-stricter-rules-for-foreign-nationals-transiting-through-canada-to-alaska.html