Highway 93 Border crossing @ Roosville, AB & Montana

I've gone through there a bunch of times and never had a wait. I've seen it lined up coming back into the States, though, but not when I came back through, never a delay (I always come back through in the evening). That's my favorite crossing. But if you to want be absolutely sure no wait, do the Chief's Mtn crossing, though you'll have to go back through Glacier, as it's on the east side. But Waterton is well worth the trip.