Ontario Provincial Highway Network

Ontario Provincial Highway Network
Highway markers for King's Highway 17, King's Highway 401, Secondary Highway 600, and Tertiary Highway 800
System information
Maintained by the MTO
Length	16,900 km[2][GIS 1] (10,500 mi)
Formed	February 26, 1920 (1920-02-26)[1]
Highway names
Types	King's Highway n (2–169) Secondary Highway n (500–673) Tertiary Road n (800–813)
System links
Ontario provincial highways Current Former 400-series

The Ontario Provincial Highway Network consists of all the roads in Ontario maintained by the Ministry of Transportation of Ontario (MTO), including those designated as part of the King's Highway, secondary highways, and tertiary roads. Components of the system—comprising 16,900 kilometres (10,500 mi) of roads and 2,880 bridges^{[GIS 1]} —range in scale from Highway 401, the busiest highway in North America, to unpaved forestry and mining access roads. The longest highway is nearly 2,000 kilometres (1,200 mi) long, while the shortest is less than a kilometre. Some roads are unsigned highways, lacking signage to indicate their maintenance by the MTO; these may be remnants of highways that are still under provincial control whose designations were decommissioned, roadway segments left over from realignment projects, or proposed highway corridors.

Predecessors to today's modern highways include the foot trails and portages used by indigenous peoples in the time before European settlement. Shortly after the creation of the Province of Upper Canada in 1791, the new government under John Graves Simcoe built overland military roads to supplement water-based transportation, including Yonge Street and Dundas Street. At the time, road construction was under the control of the township and county governments. Local township roads were financed and constructed through a statute labour system that required landowners to make improvements in lieu of taxes. Private companies constructed corduroy and later plank roads and charged tolls in the second half of the 19th century. The rising popularity of the bicycle led to the formation of the Ontario Good Roads Association, which advocated for the improvement of roads and recreation as the automobile rose to prominence.

By the early 20th century, the province had taken interest in road improvement and began funding it through counties. The increasing adoption of the automobile resulted in the formation of the Department of Public Highways of Ontario (DPHO) in 1916. The passing of the Canada Highways Act in 1919 resulted in the establishment of a provincial network of highways. The DPHO assigned internal highway numbers to roads in the system, and in 1925, the numbers were signposted along the roads and marked on maps. In 1930, provincial highways were renamed King's Highways and the familiar crown route markers created. The DPHO was also renamed the Department of Highways (DHO).

The 1930s saw several major depression relief projects built by manual labour, including the first inter-city divided highway in North America along the Middle Road, which would become the Queen Elizabeth Way in 1939. In 1937, the DHO merged with the Department of Northern Development, extending the highway network into the Canadian Shield and Northern Ontario. Significant traffic engineering and surveying through the war years, during which construction came to a near standstill, led to the planning and initial construction of controlled-access highways. The 400-series highways were built beginning in the late 1940s and numbered in 1952.

The vast majority of modern road infrastructure in Ontario was built throughout the 1950s, 1960s, and early 1970s. The cancellation of the Spadina Expressway and the introduction of the Environmental Assessment Act in the 1970s resulted in a decline in new highway construction in the decades since. In the late 1990s, nearly 5,000 kilometres (3,100 mi) of provincial highways were transferred, or "downloaded" back to lower levels of government. Few new provincial highways have been built in the early years of the 21st century, although several major infrastructure projects including the Herb Gray Parkway and expansion of Highway 69 have proceeded. Recent construction has included the controversial Bradford Bypass and Highway 413.

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