File:23 Kilometres to St. Marys, Ontario, Kings Highway 7 (21216162324).jpg

King's Highway 7, commonly referred to as Highway 7 and historically as the Northern Highway, is a provincially maintained highway in the Canadian province of Ontario. At its peak, Highway 7 measured 716 km (445 mi) in length, stretching from Highway 40 east of Sarnia in Southwestern Ontario to Highway 17 west of Ottawa in Eastern Ontario. However, due in part to the construction of Highways 402 and 407, the province transferred the sections of Highway 7 west of London and through the Greater Toronto Area to county and regional jurisdiction. The highway is now 535.7 km (332.9 mi) long; the western segment begins at Highway 4 north of London and extends 154.1 km (95.8 mi) to Georgetown, while the eastern segment begins at Donald Cousens Parkway in Markham and extends 381.6 km (237.1 mi) to Highway 417 in Kanata.

Highway 7 was first designated in 1920 between Sarnia and Guelph and extended to Brampton the following year. Between 1927 and 1932, the highway more than doubled in length as it was gradually extended eastward to Perth, where Highway 15 continued to Ottawa. In the early 1960s, that section of Highway 15 was renumbered as Highway 7. In that same decade, the Conestoga Parkway and Peterborough Bypass were constructed. During the 1970s and 1980s, many sections of Highway 7 were widened from the initial two lane cross-section to four or six lanes. Within York Region, the route was upgraded to a limited-access expressway in preparation for the construction of Highway 407.

en.wikipedia.org/wiki/Ontario_Highway_7