Autoroute 640 is a Quebec autoroute that runs across the North Shore Region from Route 344 in the Oka area to Route 138, where it ends as a four-lane expressway in Charlemagne. The road was designed to be northern bypass of the city of Montréal and was originally intended to cross the Lake of Two Mountains to connect to Autoroute 40 near Vaudreuil. It is currently 54.8 km (34.1 mi) long.