Highway 401

Highway 401
Macdonald–Cartier Freeway
Highway 401 within Southern Ontario
Route information
Maintained by the Ministry of Transportation of Ontario
Length:	828.0 km (514.5 mi)
History:	Proposed 1938 Opened December 1947 – October 11, 1968 Extended June 28 and November 21, 2015
Major junctions
West end:	Ojibway Parkway in Windsor
	E. C. Row Expressway  Highway 3 in Windsor  Highway 402 in London  Highway 403 near Highway 407 near Milton   Highway 403 / Highway 410 in Mississauga  Highway 427 in Toronto  Highway 409 in Toronto  Highway 400 in Toronto Don Valley Parkway / Highway 404 in Toronto  Highway 412 in Whitby  Highway 416 towards Ottawa
East end:	A-20 towards Montreal, QC
Location
Major cities:	Windsor, London, Kitchener, Cambridge, Mississauga, Toronto, Oshawa, Kingston and Cornwall
Highway system
Ontario provincial highways List 400-series Former ← Highway 400 Highway 402 →

Highway 407 near Milton

King's Highway 401, commonly referred to as Highway 401 and also known by its official name as the Macdonald–Cartier Freeway or colloquially as the four-oh-one, is a 400-series highway in the Canadian province of Ontario. It stretches 828.0 kilometres (514.5 mi) from Windsor in the west to the Ontario–Quebec border in the east. The part of Highway 401 that passes through Toronto is North America's busiest highway, and one of the widest. Together with Quebec Autoroute 20, it forms the road transportation backbone of the Quebec City–Windsor Corridor, along which over half of Canada's population resides and is also a Core Route in the National Highway System of Canada. The route is maintained by the Ministry of Transportation of Ontario (MTO) and patrolled by the Ontario Provincial Police. The speed limit is 100 km/h (62 mph) throughout its length, unless posted otherwise.