[hipster duck]

Responding to the OP’s proposal:

Not much different, except Vancouver would sprawl a little more, since farmland and flat, developable land wouldn’t be so scarce, especially around the Abbotsford chokepoint.

The Grand Coulee dam probably wouldn’t have been built, since the Americans probably would not have been able to convince Canada to pay for half the costs of such an astronomical project.

A Puget sound city would’ve still formed, but wouldn’t be as big as Seattle, and May have been further south.

Mt Baker would have been “our” mountain. There would probably be more infrastructure at the base.