Squalls build over Lake Erie and come up the river valley in bands, and at three in the morning the only lights moving in Niagara Falls belong to plow trucks. North Wind runs in that dark — pushing driveways open, cutting lanes across lots, shoveling the walks and stairs a blade cannot reach, spreading salt ahead of the refreeze. Snow can fall four inches an hour and then quit like a switch and start over, so the route gets run twice, sometimes three times, in a night. Nobody sees any of it; they see a clear driveway at seven and an ordinary morning. That is exactly the idea.