Predecessors to today's modern highways include the foot trails and portages used by indigenous peoples in the time before European settlement.

Local township roads were financed and constructed through a statute labour system that required landowners to make improvements in lieu of taxes.

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 the late 1990s, nearly 5,000 kilometres (3,100 mi) of provincial highways were transferred, or "downloaded" back to lower levels of government.

Industrial roads are privately owned routes with which the MTO has entered an agreement to improve or allow public access, and are not considered part of the provincial highway network.

[6][GIS 2] Three segments of freeway are part of an ongoing pilot project to test speed limits of 110 km/h in rural areas that are not subject to congestion.

[14][6] Unlike other roads in the Provincial Highway Network, the MTO is not responsible for winter maintenance nor liable for damage incurred as a result of using these routes.

[34] In 1615, French explorer Samuel de Champlain was the first European to pass through the lands between the Great Lakes, accompanied by Huron and Iroquois guides.

[35][36][37] For the next 150 years, France and Britain wrestled for control of the colony of Canada while simultaneously exploiting the land for the fur trade of North America.

[43] The Spit of Land which forms its Entrance is capable of being fortified with a few heavy Guns as to prevent any Vessel from entering the Harbour or from remaining within it. ...

John Graves Simcoe, the first Lieutenant Governor of Upper Canada, landed at Niagara on July 26, 1792, after overwintering in Quebec City,[45] from England and set forth to colonize the province in the image of Britain.

[47] Although Niagara-on-the-Lake (then known as Newark) served as the capital for a year, Simcoe moved it to what is now Toronto after July 30, 1793, at the behest of French merchant Philippe de Rocheblave,[48] following the arrival of news in May of France's declaration of war against Britain.

[46] Having reformed the Queen's Rangers, whom he fought alongside during the American War, Simcoe set out to establish military roads to connect his new capital with the Upper Great Lakes and other strategic points.

William Berczy — and the nearly 200 Pennsylvania Dutch settlers whom accompanied him from the US into Upper Canada in July 1794 — would complete the opening of the route to Bond Lake by the end of 1794.

[53] In 1798, Asa Danforth was hired by the government of Upper Canada to build a road to the Trent River, in what in now Trenton, by July 1 of the following year.

The intention was for settlers throughout the length of the roads to work on the portion fronting their lot, which was generally twenty chains, or 400 metres (1,300 ft) long.

[62] As the second township frontage along Lake Ontario also filled, the government came under pressure to open up the unforgiving terrain of the Canadian Shield to settlement and sought to establish a network of east–west and north–south roads between the Ottawa Valley and Georgian Bay.

However, by 1860, due to the unsuitability of much of the land for any kind of settlement or agriculture, the roads were almost impassable in many places, except when frozen in winter or dry in summer.

[66] Beginning in 1852, the Grand Trunk Railway gradually assembled together many of the various shortline railroads in what was soon to become Ontario to form a single route across the province, connecting Sarnia with Montreal via Toronto, by 1884.

[67] The government largely subsidized these endeavours, and funding for road construction fell to the wayside, despite the pleas of townships, villages and settlers.

[92][93][94] A 40 m (130 ft) right-of-way was purchased along the Middle Road and construction began to convert the existing sections to a divided highway.

[24][96] When widening in Scarborough reached the Highland Creek ravine in 1936, the Department of Highways began construction on a new bridge over the large valley, bypassing the former alignment around West Hill.

[99] The expressway between Highland Creek and Oshawa was also completed in this period, and opened as far as Ritson Road in December 1947, becoming the progenitor to Highway 401.

[101] Amongst some of the most difficult terrain encountered in Canada, the 266 kilometres (165 mi) of wilderness known as "the Gap" was a missing link in the Trans-Canada Highway between Nipigon and Sault Ste.

In 1963, transportation minister Charles MacNaughton announced the widening of Highway 401 in Toronto from four to a minimum of 12 lanes between Islington Avenue and Markham Road.

The battle culminated when premier Bill Davis rose in the legislature and declared "If we are building a transportation system to serve the automobile, the Spadina Expressway would be a good place to start.

[143][144][145] As part of a series of budget cuts initiated by premier Mike Harris under his Common Sense Revolution platform in 1995, numerous highways deemed to no longer be of significance to the provincial network were decommissioned and responsibility for the routes transferred to lower levels of government, a process referred to as downloading.

These transfers were performed under the reasoning that they served a mostly local function, as a cost-saving measure and as part of a broader exchange of responsibilities between the province and its municipalities.

[164] Construction began in 2012 on a provincially operated 65-kilometre (40 mi) long extension to the 407 ETR, known as Highway 407 East (or 407E) during planning, with the project undertaken in two separate phases.

The MTO took advantage of this opportunity to extend Highway 401 to the Canada–US border and began an environmental impact assessment on the entire project in late 2005.