The Canadian route on the Trans Canada Highway and BC-1 is both the fastest and shortest route at 761 miles and an estimated 8 minutes faster then the drive through Spokane.
Cranbrook, Canada is the halfway point between Calgary, Canada and Spokane, Washington. There is about 434 miles between Calgary and Spokane.
Calgary
24W to 57N to 64W to 70W to 435N to 29N to 90W to 15N
Calgary is the major Canadian city located above Spokane. It is situated in the province of Alberta.
Roughly 8 hours Drive
Sweetgrass, Montana
691 km - about 8 hours 30 mins
The distance is approximately 430 road miles.
1283km according to the University of Calgary WebPages
The shortest route is on I-90 W.
It is 426 miles according to Google Maps.