To the south of Woodstock, Highway 401 curves northeast and encounters the western terminus of Highway 403.After this 10 km (6.2 mi) gap, the highway interchanges with the Highway 407 Express Toll Route.The part of Highway 401 that passes through Toronto is North America's busiest highway, 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.In 1965 it was given a second designation, the Macdonald–Cartier Freeway, in honour of two Fathers of Confederation.At the end of 1968, the Gananoque–Brockville section was bypassed and the final intersection grade-separated near Kingston, making Highway 401 a freeway for its entire 817.9-km length.In 2011, construction began on a westward extension called the Right Honourable Herb Gray Parkway.This new route follows, but does not replace, former Highway 3 between the former end of the freeway and the E. Row Expressway, at which point it turns and parallels that route towards the site of the future Gordie Howe International Bridge.
By the end of 1952, three individual highways were numbered "Highway 401": the partially completed Toronto Bypass between Weston Road and Highway 11 (Yonge Street); Highway 2A between West Hill and Newcastle; and the Scenic Highway between Gananoque and Brockville, now known as the Thousand Islands Parkway.
The expansive twelve-plus-lane collector–express system will also be extended west through Mississauga to Milton and east through Ajax and Whitby.
Highway 401 extends across Southwestern, Central and Eastern Ontario.
is a controlled-access 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.