Ontario Highway 427

Highway 427
Highway 427 highlighted in red
Route information
Maintained by Ministry of Transportation of Ontario
Length	27 km (17 mi)
Existed	December 4, 1971[1]–present
Major junctions
South end	Queen Elizabeth Way / Gardiner Expressway – Toronto Continues as Browns Line; however, according to the King's Highway Website, the south end is Evans Avenue.
Major intersections	Highway 401 – Toronto  Highway 409 – Toronto/Mississauga  407 ETR – Vaughan
North end	Regional Road 25 (Major Mackenzie Drive) – Vaughan
Location
Country	Canada
Province	Ontario
Highway system
Ontario provincial highways Current Former 400-series
← Highway 420 → Queen Elizabeth Way

King's Highway 427 (pronounced "four twenty-seven"), also known as Highway 427 and colloquially as the 427, is a 400-series highway in the Canadian province of Ontario that runs from the Queen Elizabeth Way (QEW) and Gardiner Expressway in Toronto to Major Mackenzie Drive (York Regional Road 25) in Vaughan. It is Ontario's second busiest freeway by volume and the third busiest in North America, behind Highway 401 and Interstate 405 in California.^[2][3] Like Highway 401, a portion of the route is divided into a collector-express system with twelve to fourteen continuous lanes. Notable about Highway 427 are its several multi-level interchanges; the junctions with the QEW/Gardiner Expressway and Highway 401 are two of the largest interchanges in Ontario and were constructed between 1967 and 1971, while the interchanges with Highway 409 and Highway 407 were completed in 1992 and 1995, respectively.

Highway 427 is one of two complete north-south freeways in Toronto, the only other one being Highway 404/Don Valley Parkway serving North York and Scarborough. Highway 427 serves as a major traffic route for the western portion of Toronto (Etobicoke), the northeastern portion of Mississauga (Malton), the southeastern portion of Brampton (Claireville), and the western portion of Vaughan (Woodbridge). The section of Highway 427 between Highway 401 and Dundas Street is a heavily traversed transit corridor; the 1.61-kilometre (1.00 mi) stretch between Burnhamthorpe and Rathburn saw an average of over 400,000 vehicles and over 5,000 buses per day in 2016, including express buses from GO Transit, MiWay, and the Toronto Transit Commission (TTC).^[4] The freeway is also the main feeder to Toronto Pearson International Airport from the north and south, as a considerable amount of traffic from Highway 401 (eastbound), the QEW/Gardiner Expressway, and Highway 407 make use of the route for airport access.

First designated in 1972, Highway 427 assumed the recently completed 12-lane collector-express freeway of Highway 27, as well as a short freeway north of Highway 401 known as the Airport Expressway. Both routes were upgraded throughout the 1950s and 1960s, eventually becoming intertwined into the present configuration in 1972. The freeway was extended north from Pearson Airport to Highway 7 over the following twenty years. Construction of an extension north to York Regional Road 25 (Major Mackenzie Drive) began in 2017 and was opened on September 18, 2021.