400-series Highways - Numbering

Numbering

The "400-series" numbers were first introduced in 1952 to designate the province's controlled-access highways, which were previously referred to by name.

Although the QEW has no posted highway number, it is considered to be part of the 400-series highway network. The Ministry of Transportation of Ontario designates the QEW as Highway 451 for internal purposes; this designation never appears on maps or highway signs.

400-series highways receive their numeral designations in one of two ways. The original method was sequential numbering starting at 400 and working up to 409. The first three 400-series highways numbered accordingly were Highway 400, Highway 401 and Highway 402 – originally known as the Barrie-Toronto Highway, Highway 2A, and the Blue Water Bridge Approach respectively. Since then, additional highways have been constructed using sequential numbering from 403 to 409. Although there were plans for a Highway 408, it was never constructed. Highway 407 (now 407 ETR) received its designation in the 1960s when it was planned and land was acquired for it, although construction did not begin until 1987.

The later method of 400-series numbering after 1970 was to assign a 400 designation to an upgrade or bypass of an existing highway. For example, the section of Highway 427 between the QEW and Highway 401 was the original routing of Highway 27 between the QEW and Highway 401 before it was upgraded to a freeway, while Highway 427 north of Highway 401 is a bypass of Highway 27. Highway 416 and Highway 417, meanwhile, were the original routings of Highways 16 and 17, respectively, in Eastern Ontario. In addition, some 400-series highways are given designations based on the existing highways they bypass. For instance, Highway 410 and Highway 420 were both freeway bypasses of Highway 10 and Highway 20, respectively.