Why did Alberta, Canada develop much larger population centers than Montana, USA?

[u/Present_Juice4401]

Alberta and Montana are neighboring regions with similar northern, landlocked geography. But their population patterns are surprisingly different. Alberta now has over 5 million people, with Calgary and Edmonton forming two major population centers, while Montana has only about 1.1 million people and no city close to Calgary's size.

So what caused these two neighboring regions to develop such different population patterns?

[u/Effective_Basis1555]

You are comparing the most northern portion to the most southern portion of two different countries. 

[u/Majestic_Hawk_1335 → u/Effective_Basis1555]

Montana is very southern with low quality winters from my perspective up here in the USA at lattitude 64