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 connects the Queen Elizabeth Way (QEW) and Gardiner Expressway with York Regional Road 7 (formerly Highway 7) via Highway 401. An arterial extension, known as York Regional Road 99, continues north to Zenway Boulevard. It is Ontario's second busiest freeway by volume and third busiest in North America, behind Highway 401 and Interstate 405 in California. 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 QEW 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 are more recent and were completed in 1992 and 1995, respectively.