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 theMTO
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

TheOntario Provincial Highway Network consists of all the roads inOntario maintained by theMinistry 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 fromHighway 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 areunsigned highways, lacking signage to indicate their maintenance by the MTO; these may be remnants of highways that are still under provincial control whose designations weredecommissioned, roadway segments left over from realignment projects, or proposed highway corridors.

Predecessors to today's modern highways include the foot trails andportages used byindigenous peoples in the time before European settlement. Shortly after the creation of the Province ofUpper Canada in 1791, the new government underJohn Graves Simcoe built overland military roads to supplement water-based transportation, includingYonge Street andDundas Street. At the time, road construction was under the control of thetownship andcounty 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 constructedcorduroy and laterplank roads and chargedtolls 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 theCanada 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 renamedKing'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 alongthe Middle Road, which would become theQueen Elizabeth Way in 1939. In 1937, the DHO merged with theDepartment of Northern Development, extending the highway network into theCanadian Shield andNorthern Ontario. Significant traffic engineering and surveying through thewar years, during which construction came to a near standstill, led to the planning and initial construction ofcontrolled-access highways. The400-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 theSpadina Expressway and the introduction of theEnvironmental 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 theHerb Gray Parkway and expansion ofHighway 69 have proceeded. Recent construction has included the controversialBradford Bypass andHighway 413.

In Ontario, all public roads are legally considered highways under theHighway Traffic Act (HTA), which sets forth regulations for traffic, or therules of the road.^[3] ThePublic Transportation and Highway Improvement Act (PTHIA) sets forth the regulations concerning roads that are under the authority of the Province of Ontario. The act distinguishes and sets out the applicability of the HTA to provincial highways, which are designated as part of The King's Highway (primary), a secondary highway, or a tertiary road. Tertiary roads may also be designated as a resource road, allowing for vehicles otherwise prohibited from public roads. 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.^[4] The407 ETR is likewise not considered part of the provincial highway network. While it is still subject to the rules set forth by the HTA, it is otherwise governed independently under the legislation of theHighway 407 Act.^[5]

Speed limits on provincial highways are legislated by sections of the road, and vary between 50 km/h (30 mph) and 110 km/h (70 mph). Freeways, including the 400-series highways, are generally signed at 100 km/h (60 mph), although sections exist that are signed lower.^{[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. A fourth segment, located inNorthern Ontario, was set to be announced in 2020, but has been delayed since.^[7]

Ontario uses two distinct shapes of signage to mark the King's Highways. Confirmation markers, orreassurance markers, are utilized along the designated road to confirm (near intersections) or reassure (elsewhere) drivers that they are on the correct route. The markers, known asshields, feature the route number within an outline in theshape of a shield, topped by aSt Edward's Crown. In other cases, particularly when approaching the junction of another highway, a squarecrown marker is used, featuring the route number within an outline of the St Edward's Crown, paired with an arrow plate; exit signs on freeways and at major junctions also use this crown symbol. For secondary highways, the route number is within an outline of anisosceles trapezoid, while tertiary roads place the number within an outline of a rectangle. When these markers appear along or at an intersection with the indicated highway, they feature black text on a reflective white background. There are two exceptions to this: The QEW, which features blue text on a yellow background; and the provincially maintained section of the tolledHighway 407, which feature white text on a blue background, with an orange plate withTOLL below in black.Signs prior to 1993 had the words "The King's Highway" below the crown, but current versions do not have the words.^[8]

In addition to regular highway markers, there are trailblazers, which indicate a routetowards that highway. These are the same shape as their corresponding highway marker. Trailblazers for the King's Highway, which can be shields or crowns, feature white text on a reflective green background, with the exception of trailblazers for the QEW, which feature yellow text on a reflective blue background. For secondary highways, trailblazers simply add the word "TO" above the route number.^[8]

Since August 2004, "Highway of Heroes" shields featuring a diagram of apoppy have been posted along Highway 401 betweenToronto andCFB Trenton. These were erected to honour fallen Canadian soldiers, whose bodies were repatriated fromAfghanistan in funeral convoys along that stretch of the highway.^[9]

A King's Highway junction shield

A blue-on-yellow QEW reassurance marker

A King's Highway toll route shield with toll tab

A trailblazer shield

Queen Elizabeth Way trailblazer

Highway of Heroes shield

A 407 Express Toll Route (407 ETR) reassurance marker

407 ETR trailblazer

Ontario has several distinct classes of highways:^{[GIS 3]}

The King's Highway is the primary highway network of Ontario, and constitutes the majority of the principal inter-urban roadways in the province. As a whole, it is referred to in the singular form as opposed to as a group of its parts (i.e. "the King's Highway", not "the King's Highways").^[4][6]Individual highways are known as "part of the King's Highway" or "the King's Highway known asn".^[6][10]However, in common parlance they are simply referred to as "Highwayn".^[11] Ontario highways rank second safest in North America for fatality rates, with 0.55 fatalities per 10000 licensed drivers in 2019.^[12] The phrase "King's Highway" is used regardless of the gender of the monarch.

The 400-series highways and the QEW form the backbone of the King's Highway, with other routes numbered from 2 to 148.^[2] The Ministry of Transportation never designated a Highway 1.^[13]Some highway numbers are suffixed with a letterA ("alternate route"),^[14]B ("business route"),^[15]orN ("new route").^[16]In the past, there have also been routes withC andS ("scenic route") suffixes.^[17][18]The entire King's Highway network is fully paved.^[14]The term "the King's Highway" was first adopted in place of "provincial highway" in 1930, and signs similar to the current design replaced the previous triangular signs at that time.^[19][20]Some legislative acts refer to roads that are under the jurisdiction of the province as "provincial highways".^[21]

The 400-series highways are a network of controlled-access highways throughout thesouthern portion of Ontario, forming a special subset of the provincial highway network. They are analogous to theInterstate Highway System in theUnited States or theAutoroute system of neighbouringQuebec, and are regulated by the MTO.^[22]The 400-series designations were introduced in 1952, although Ontario had been constructing divided highways for two decades prior.^[23]Initially, only Highways 400, 401 and 402 were numbered; other designations followed in the subsequent decades.^[24]

While older freeways have some lapses in safety features, contemporary 400-series highways havedesign speeds of 130 km/h (81 mph),speed limits of 100 km/h (62 mph), various collision avoidance and traffic management systems, and several design standards adopted throughout North America.^[25]Of note are theOntario Tall Wall median barrier and theParclo A-4 interchange design, the latter which became standard in the design for the widening of Highway 401 through Toronto in 1962. The Institute of Traffic Engineers subsequently recommended this design to replace thecloverleaf interchange throughout North America.^[26][27]

Secondary highways exist solely within the districts of Northern Ontario that lack acounty road system, to which they are analogous. For the purposes of MTO clasification, "Northern Ontario" refers to Districts ofParry Sound andNipissing and those farther north - those Districts obtaining highway funding from Ontario Ministry of Northern Development and Mines. They generally serve to connect remote communities to the King's Highway, or to interconnect the King's Highway. A few secondary highways remaingravel-surfaced, although most have been paved.^[14]The speed limit on nearly all of these routes is 80 km/h (50 mph), althoughHighway 655 is posted at 90 km/h (55 mph).^[6]

The Secondary Highway system was introduced in 1956 to service regions in Northern andCentral Ontario, though it onceincluded a route as far south as Lake Ontario. Many routes that would become secondary highways were already maintained by the province as development roads prior to being designated.^[28][29]Since 1998, none have existed south of the districts ofParry Sound andNipissing.^[30]Secondary highways are numbered in the 500s and 600s, with existing highways numbered between 502 and 673.^[2][28]

Tertiary roads are remote routes entirely within Northern Ontario that provide access to resources (e.g. mining and forestry). Tertiary roads are numbered in the 800s, with the five existing highways numbered between 802 and 811. Most of these roads are gravel-surfaced and of low-standard. The speed limit on these routes is 80 km/h (50 mph), although design standards generally prevent such.^[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.^[4]The MTO introduced the Tertiary Road system in 1962.^[31]With the exception ofHighway 802, none end in settlements.

TheTrans-Canada Highway (TCH) forms several major routes across Canada. The provincial governments are entirely responsible for signage and maintenance of the routes, except throughNational Parks. It is signed with distinctive green markers with a whitemaple leaf on them throughout Canada. While other provinces generally place a highway number within the maple leaf of the TCH marker (with a shared "Highway 1" designation across thewestern provinces), Ontario places them below or beside provincial shields and either leaves them blank or inserts a name instead; these are theCentral Ontario Route,Georgian Bay Route,Lake Superior Route,Northern Ontario Route andOttawa Valley Route.

Several portions of the King's Highway are designated as part of the Trans-Canada Highway system within Ontario, with the TCH having a main route and several branches, often only following sections of any given provincial highway. They are:

In addition to these classes of highways, the MTO maintains other roads, such as resource roads or industrial roads, that are of strategic importance to the provincial government. These roads are designated with 7000-series numbers for internal inventory purposes, though they are not publicly marked as such. They are often, but not always, former highway segments which were decommissioned as a King's Highway, but remain important as connecting routes to communities or other highways in areas without municipal governance.^[14]There were formerly several designatedOntario Tourist Routes that were located throughout the entire province.^[32]However, beginning in February 1997, Tourism-Oriented Directional Signs (TODS) began to appear on highways.^[33]Tourist Routes no longer appeared on maps after 1998.^[30]

Prior to the arrival of Europeans in the 17th century, transportation across what became Ontario was generally via the thousands of lakes and rivers. Short trails existed between bodies of water, known as aportage or carrying place, as well as along the shorelines of the larger lakes.^[34]In 1615, French explorerSamuel de Champlain was the first European to pass through the lands between theGreat Lakes, accompanied byHuron andIroquois guides. His emissaryÉtienne Brûlé as well asFranciscanRécollets such asJoseph Le Caron andJoseph de La Roche Daillon were the first to explore various lands of the area, all with the assistance of the local First Nations.^[35][36][37]For the next 150 years, France and Britain wrestled for control of thecolony of Canada while simultaneously exploiting the land for thefur trade of North America.^[34]This culminated in the globalSeven Years' War that ended with the signing of theTreaty of Paris in 1763, which ceded Canada to the British.^[38]

The colony of Canada was renamed theProvince of Quebec until 1791, when it was divided intoUpper Canada (modern Southern Ontario) andLower Canada (modern Southern Quebec) by theConstitutional Act.^[39]This was done to provide a British-style governance to theUnited Empire Loyalists fleeing north following theAmerican Revolution.^[40]In addition to the native portages and lake shore trails, routes developed alongside significant rivers such as theSt. Lawrence,Ottawa,Humber andGrand Rivers. These meandering trails followed the lay of the land, as opposed to the straighttangents of the surveyed roads yet to come. Some roads in Ontario still closely follow these early Native and European trails,^[41][42]including the Kente Portage Trail (Old Portage Road) inCarrying Place, the oldest continuously used road in the province.^[43]

John Graves Simcoe, the firstLieutenant Governor of Upper Canada, landed at Niagara on July 26, 1792, after overwintering inQuebec City,^[45]from England and set forth to colonize the province in the image of Britain.^[46]The ambitiousabolitionist statesman, whom served the British during theAmerican Revolutionary War, was appointed to lead the new colony on September 12, 1791.^[47]AlthoughNiagara-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 merchantPhilippe de Rocheblave,^[48] following the arrival of news in May of France'sdeclaration of war against Britain.^[46]

Having reformed theQueen'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.^[49]The first road he ordered built was Dundas Street, from the head of Lake Ontario near present-dayDundas to the forks of theThames River in present-dayLondon. His Rangers began work on this route on September 10, 1793.^[50]Between September 25 and October 14, Simcoe travelled with native guides toPenetanguishene and back. Following the advice of anOjibwa named Old Sail, the return voyage followed the east branch of theHolland River and thence south to Toronto (known as York from 1793 to 1834); this would become the route ofYonge Street.^[51]

Simcoe's Rangers would commence "run[ning] the line of the new road" with Surveyor GeneralAugustus Jones in February 1794.^[52]By mid-May, the Rangers had cleared and marked 14 lots fromEglinton Avenue to just north ofSheppard Avenue before being redirected to defendFort Miami.William Berczy — and the nearly 200Pennsylvania Dutch settlers whom accompanied him from the US into Upper Canada in July 1794 — would complete the opening of the route toBond Lake by the end of 1794. The remainder toHolland Landing was opened by the Rangers, under the supervision of Augustus Jones, between December 28, 1795, and February 16, 1796.^[53]

In 1798,Asa Danforth was hired by the government of Upper Canada to build a road to theTrent River, in what in nowTrenton, by July 1 of the following year. He began at theDon River, whereQueen Street crosses it today, on June 5 of that year, and proceeded east.^[54][55]Danforth was paid $90 per mile to cut a road 10 metres (33 ft) wide, of which the middle half was cut to the level of the ground. He was also to build 5.0-metre (16.5 ft)-wide causeways "wherever necessary" and ensure that slopes were gradual enough for a sleigh or carriage to pass. He completed the first 101 kilometres (63 mi) toPort Hope by December.^[56]The government ultimately decided that his road was unacceptable, and reportedly paid him less than owed. Portions of Danforth's road were later incorporated intoHighway 2, as well as several local roads inScarborough.^[57]

The majority of settlers up to this point wereUnited Empire Loyalists — settlers of theThirteen Colonies loyal to Britain who fled north to the new colony. These pioneers endured starting anew in untamed wilderness, with little provisions beyond what they could carry.^[58]Many were strategically placed along Yonge Street and Dundas Street, and given the duty of clearing half the width of a road along the front of their property lot. Settlers were responsible for the upkeep, and often the building of roads in this period, with each male over 21 years of age required to perform three or more days ofstatute labour per year, based on the value of their land. The intention was for settlers throughout the length of the roads to work on the portion fronting their lot, which was generally twentychains, or 400 metres (1,300 ft) long.^[59][60]However, many lots were given to absent clergymen and English nobles, resulting in these "roads" being poorly maintained quagmires of mud.^[61]

During the early 1800s, the government of Upper Canada appropriated settlers to various lots which had been surveyed along the lake shores ofLake Erie andLake Ontario. The townships established along these fronts contained generally fertile land composed ofglacial till and clay-richloam. As these townships filled up, business opportunities presented themselves for investors to purchasenative lands and open them to settlement. TheCanada Company was the most successful of these ventures and brought settlers to vast areas of land in what would becomeSouthwestern Ontario by building routes such asHuron Road andToronto–Sydenham Road during the 1830s and 1840s.^[62]

As the second township frontage along Lake Ontario also filled, the government came under pressure to open up the unforgiving terrain of theCanadian Shield to settlement and sought to establish a network of east–west and north–south roads between theOttawa Valley andGeorgian Bay. This area was known as theOttawa–Huron Tract.^[63][59]In 1847, an explorationsurvey was carried out byRobert Bell to lay out the lines that would become the Opeongo, Hastings, and Addingtoncolonization roads. The Public Lands Act, passed in 1853, permitted the granting of land to settlers who were at least 18. Those settlers who cleared at least 12 acres (4.9 ha) within four years, built a house within a year, and resided on the grant for at least five years would receive the title to that land. The government subsequently built over 1,600 kilometres (1,000 mi) of roads over the following 20 years to provide access to these grants, although the roads were often little more than a trail cut through the forest wide enough for a wagon.^[64]

Like the lands to the south, statute labour was responsible for the majority of road development and maintenance. 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. The large timber drive that was clearing the forests of the Ottawa–Huron Tract in this period contributed somewhat to road construction and maintenance, but the settlers themselves were largely left to their own resolve.^[64][59]Statute labour was gradually abolished around the turn of the 20th century.Malden Township was the first to do so in 1890,^[65]and a majority of other municipalities followed suit by the 1920s. However, the law remained in place provincially until being officially repealed on January 1, 2022.^[66]

Beginning in 1852, theGrand Trunk Railway gradually assembled together many of the variousshortline railroads in what was soon to become Ontario to form a single route across the province, connectingSarnia with Montreal via Toronto, by 1884. Simultaneously, theCanadian Pacific Railway constructed a route across northern Ontario, connecting Thunder Bay with Ottawa by 1880.^[67]The government largely subsidized these endeavours, and funding for road construction fell to the wayside, despite the pleas of townships, villages and settlers.^[59][68]In 1896, the provincial Instructor in Road Making reported "It is doubtful if there is a mile of true macadam road in Ontario outside of a few towns or cities ... by far the greatest part of the milage of the province is mud, ruts and pitch-holes ..."^[69]

The cries of municipalities went unanswered, but it would not stop their ambition. Coupled with the increasing adoption of the bicycle as a means of transport, and the desire of farmers to get their goods to market quicker, theOntario Good Roads Association was formed in 1894 by representatives from numerous townships, villages and cities. TheGood Roads Movement encouraged education on the building of proper roads, and later equipment to aid in the improvement of roads, as well as lobbying the various levels of government to fund road development and maintenance. Members would travel from town to town and across the countryside, espousing the value of properly built roads to communities.^[71][72]

Two of the most influential members in its early days wereArchibald William Campbell and Dr.Perry Doolittle.^[71][73]"Good Roads" Campbell would become the province's first Instructor in Roadmaking when the position was established on April 15, 1896, under theDepartment of Agriculture.^[74] Doolittle, a Toronto physician, became one of the earliest automobile owners in Canada, and spurred the good roads movement.^[73] He became the first person to drive across Canada in 1925, utilizing the railways around Lake Superior where no roads existed, and is known as the "Father of the Trans-Canada Highway".^[70]

The arrival of automobiles rapidly changed the approach to roads and roadbuilding in the first years of the 20th century. In 1900, the provincial Instructor in Roadmaking was renamed as the Commissioner of Public Highways in 1900, as well as the Deputy Minister in the new Department of Public Works in 1905.^[75] The first legislation on driving was introduced in 1903, and included the first speed limits (15 miles per hour (24 km/h)). The first license plates were created that year, the first highway patrol established in 1907, licences forchauffeurs in 1909 (regular drivers did not require a licence until 1927), and safety requirements such as headlights. These laws culminated in the creation of theHighway Traffic Act in 1923.^[76]

Roadbuilding advanced considerably, with the most notable project of the period being the Toronto–Hamilton Highway, the first paved intercity road in Ontario. The highway was chosen to run along themacadamized old Lake Shore Road between the two cities, instead of Dundas Street to the north, because of the numerous hills encountered along Dundas.^[77]In November 1914, the proposed highway was approved,^[78]and work began quickly to construct the road known today asLake Shore Boulevard andLakeshore Road from Toronto to Hamilton. The road was finished in November 1917, 5.5 metres (18 ft) wide and nearly 64 kilometres (40 mi) long, becoming the first concrete road in Ontario.^[77]The highway became the favourite drive of many motorists, and it quickly became a tradition for many families to drive it every Sunday.^[79]

Roads and highways in Ontario were given their first serious consideration by the provincial government when the Department of Public Highways (DPHO), predecessor to the modernMinistry of Transportation of Ontario, was established on January 17, 1916. Until then, the majority of the primary roads through southern Ontario formed part of the county road systems. The Department of Public Works paid up to 60% of the construction and maintenance costs for these roads, while the counties were responsible for the remaining 40%.^[80]The Ontario government passed an act in 1917 to permit the newly formed Department of Public Highways (DPHO) to take over (or assume) responsibility and upkeep of a provincial highway system. The initial system, betweenWindsor andQuebec, was bookended by branches to Niagara andOttawa.^[81]In 1919, the federal government passed theCanada Highways Act, which provided $20,000,000 to provinces under the condition that they establish an official highway network; up to 40% of construction costs would be subsidized. The first network plan was approved on February 26, 1920. At this time, Campbell was now the Federal Commissioner of Highways.^[80]

Until the summer of 1925, Ontario highways were named rather than numbered. When route numbering was introduced, the following numbers were allotted:^[82][83]

The number of Provincial Highways—as they were initially known—expanded quickly from there. The provincial highway network did not extend into theCanadian Shield norNorthern Ontario initially, andTrunk Roads in the north were instead under the mandate of theDepartment of Northern Development. The two primary trunk routes were extensions ofHighway 11 andHighway 17, toNorth Bay andSault Ste. Marie, respectively.^[80]Seeking to open the far north, construction of a road to connect North Bay andCochrane began in 1925,^[84]The new gravel highway was officially opened on July 2, 1927,^[85] by Minister of Lands and ForestsWilliam Finlayson. He suggested at the opening that the road be named theFerguson Highway in honour of premier Ferguson. The name was originally suggested by North Bay mayor Dan Barker.^[86]Despite the official opening, a section betweenSwastika and Ramore wasn't opened until August.^[87]The Ferguson Highway name was also applied to the Muskoka Road between Severn Bridge and North Bay.^[85]

During the 1920s, the DPHO began to examine possible remedies to chronic congestion on along Highway 2, particularly between Toronto and Hamilton (Lakeshore Road), eventually deciding upon widening the roadway midway between Lakeshore Road andHighway 5 (Dundas Street), orthe Middle Road. It was to be more than twice the width of Lakeshore Road at 12 m (39 ft) and would carry two lanes of traffic in either direction.^[88][89]Construction on what was then known as theQueen Street Extension west of Toronto began in early 1931.^[90]Before the highway could be completed,Thomas McQuesten was appointed the new minister of the renamed DHO, withRobert Melville Smith as deputy minister, following the1934 provincial elections.^[24]

Smith, inspired by the Germanautobahns—new "dual-lanedivided highways"—modified the design for Ontario roads,^[91]and McQuesten ordered the Middle Road be converted into this new form of highway.^[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. Work also began on Canada's firstinterchange at Highway 10.^[95]The Middle Road was ceremoniously renamed theQueen Elizabeth Way during the1939 royal tour of Canada, taking its name fromQueen Elizabeth The Queen Mother, and was completed between Toronto and Niagara Falls on August 26, 1940.^[88]

Beginning in 1935, McQuesten applied the concept of a dual-highway to several projects along Highway 2, including along Kingston Road in Scarborough Township.^[24][96]When widening in Scarborough reached theHighland Creek ravine in 1936, the Department of Highways began construction on a new bridge over the large valley, bypassing the former alignment aroundWest Hill.^[97]From here the highway was constructed on a new alignment to Oshawa, avoiding construction on the congested Highway 2.^[98] Asgrading and bridge construction neared completion on the new highway between West Hill and Oshawa in September 1939,World War II broke out and gradually tax revenues were re-allocated from highway construction to the war effort.^[24]

As the war came to a close, planning began in 1945 on the Toronto–Barrie Highway to ease the congestion on the parallel routes ofHighway 11 andHighway 27. The highway followed a completely new alignment, and featured interchanges at nearly all crossroads. Construction of an extension around Barrie began in 1950, and the completed freeway was opened on July 1, 1952.^[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.^[98]

When Ontario signed the Trans-Canada Highway Agreement on April 25, 1950, it had already chosen a Central Ontario routing via Highway 7, Highway 12,Highway 103 and Highway 69;^[100]Highway 17 through theOttawa Valley was announced as a provincially funded secondary route of the Trans-Canada the following day.^[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 betweenNipigon andSault Ste. Marie.^[102] Construction began in 1956,^[103]and it was completed and ceremoniously opened to traffic on September 17, 1960, uniting the two segments and completing the route of Highway 17 from the Manitoba border to the Quebec border.

The construction boom following the war resulted in many new freeway construction projects in the province. The Toronto–Barrie Highway (Highway 400), Trans-Provincial Highway (Highway 401),^[24]a short expansion of Highway 7 approaching theBlue Water Bridge in Sarnia (Highway 402),^[104]and an expansion of Highway 27 (eventually designated asHighway 427 by the mid-1970s) into part of the Toronto Bypass were all underway or completed by the early 1950s.^[24] Seeking a way to distinguish the controlled-access freeways from the existing two-lane King's Highways, the Department of Highways created the 400-series designations in 1952. By the end of the year, Highway 400, 401, and 402 were numbered, although they were only short stubs of their current lengths.^[105]Highway 401 was assembled across the province in a patchwork fashion,^[24]becoming fully navigable between Windsor and the Quebec border on November 10, 1964;^[106]Highway 400 was extended north toColdwater on Christmas Eve 1959;^[107]Highway 402 was extended to London between 1972 and 1982.^[108][109]

In addition to this network backbone, plans for additional 400-series highways were initiated by the late 1950s, comprising the Chedoke Expressway (Highway 403) throughHamilton;^[110]theDon Valley Parkway Extension (Highway 404) northward from the soon-to-be constructed Toronto expressway;^[111]Highway 405 to connect with the American border nearSt. Catharines;^[112]Highway 406 south from St. Catharines toWelland;^[113]Highway 407 encircling the Greater Toronto Area (GTA), though not built for another 40 years;^[114]Highway 409 to connect Highway 401 withToronto International Airport;^[115]and The Queensway (Highway 417) through Ottawa.^[116]The first sections of these freeways were opened in 1963,^[117]1977,^[118]1963,^[117] 1965,^[119]1997,^[120]1974,^[121]and 1960,^[122]respectively. In 1963, transportation minister Charles MacNaughton announced the widening of Highway 401 in Toronto from four to a minimum of 12 lanes betweenIslington Avenue andMarkham Road.^[98] Construction began immediately; while the plan initially called for construction to end in 1967, it continued for nearly a decade. At least four lanes were always open during the large reconstruction project, which included complex new interchanges at Highway 27, Highway 400, the planned Spadina Expressway and the Don Valley Parkway.^[24]

Throughout the mid-to-late 1960s, the provincial government also funded numerous urban expressways, including theConestoga Parkway inKitchener–Waterloo, theThunder Bay Expressway in Thunder Bay,Highbury Avenue inLondon, theHanlon Expressway intoGuelph and most infamously theSpadina Expressway intoDowntown Toronto. While the others were built, the Spadina became a heated debate in the late 1960s betweenMetropolitan Toronto and urban activists includingJane Jacobs. The battle culminated when premierBill 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. But if we are building a transportation system to serve people, the Spadina Expressway is a good place to stop."^[123]

The cancellation of the Spadina Expressway led to the demise ofother proposed expressways in Toronto and elsewhere in the province, as well as a decline in new road building proposals.^[124]It remains, to this day, a controversial decision.^[125][126]The Environmental Assessment Act, introduced in 1975, further restricted new highway building,^[127] and as a result the 1970s and 1980s saw less new highway construction compared to prior decades.

Despite this, several existing freeways were extended or expanded, including Highway 402 from Sarnia to London between 1972 and 1982,^[128][129]Highway 403 through Mississauga between 1978 and late 1982,^[130][131]theDon Valley Parkway as Highway 404 north from Toronto toNewmarket between 1976 and 1989,^{[132][133][134]}Highway 406 throughSt. Catharines between 1977 and 1984,^[135][136]Highway 417 from Ottawa to the Quebec boundary between 1970 and late 1975,^[137][138]and the expansion of Highway 27 into Highway 427 between 1968 and late 1971,^[139][140]as well as its extension from Highway 401 to Highway 7 between 1976 and 1991.^[141][142]Highway 410 was also built, initially as a two lane road, between 1975 and late 1978.^{[143][144][145]}

As part of a series of budget cuts initiated by premierMike Harris under hisCommon 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 asdownloading. Several thousand kilometres of provincially maintained highways were transferred to the variousmunicipalities in which they are located. 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.On April 1, 1997, 1,767.6 kilometres (1,098.3 mi) of highways were removed from the King's Highway system.^[146]This was followed by the removal of 3,211.1 kilometres (1,995.3 mi) on January 1, 1998,^[147]for a total of 4,978.7 kilometres (3,093.6 mi); the move was criticized by the media.^[148][149]

In the 1980s and 1990s,Highway 416 was constructed through a process known as twinning in which a secondcarriageway is built parallel to the existing road. In addition, existing intersections were rebuilt asgrade-separated interchanges.^[150]Highway 16 New was built during the 1960s and 1970s, establishing the right-of-way and alignment of a future freeway as a two-lane highway.^[151]Planning for a connection toHighway 417 began in 1987,^[152]and was completed on July 31, 1997.^[153][152]Work to twin Highway 16 New began in mid-1996,^[154]and was completed in sections between June 1997,^[155]and September 1999, after which nearly the entire length of Highway 16 was redesignated as Highway 416.^[156]

In recent years, highway construction has generally been limited to the expansion of existing highways, principal among them Highway 11, Highway 400/69, and the Herb Gray Parkway extension of Highway 401 into Windsor. The four-laning of 240 kilometres (150 mi) of Highway 11 between Barrie and North Bay was a long-term expansion that was completed August 8, 2012, having been worked on since 1955.^{[157][158][159]}The four-laning of Highway 69, which will be replaced by Highway 400, has progressed northward fromWaubaushene since 1991,^[160]reaching as far asNobel on October 26, 2010.^[161]Work has also progressed south from Sudbury since 2005,^[162][163]and as of 2022 has reached theFrench River, leaving a 68-kilometre (42 mi) gap of two-lane highway between Toronto and Sudbury.^[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. Phase 1 was opened on June 20, 2016, consisting of a 22-kilometre (14 mi) extension to Harmony Road in Oshawa, as well as the 10-kilometre (6.2 mi) Highway 412.^[165] The extension was free of tolls until February 1, 2017.^[166]Phase 2A, which opened on January 2, 2018, added a 9.6-kilometre (6.0 mi) extension to Taunton Road at the future Highway 418 interchange.^[167] Phase 2B, which opened on December 9, 2019, added a 23.3-kilometre (14.5 mi) extension to Highway 35 and Highway 115, as well as the 12.8-kilometre (8.0 mi) Highway 418.^[168]

In 2004, a joint announcement by thefederal government of the United States andGovernment of Canada confirmed a new Canada–U.S. border crossing would be constructed betweenDetroit and Windsor. The MTO took advantage of this opportunity to extend Highway 401 to the Canada–US border and began anenvironmental impact assessment on the entire project in late 2005.^[169]Despite protest from area residents,^[170]as well as a dismissed lawsuit fromAmbassador Bridge ownerMatty Moroun,^[171][172]it was announced on May 1, 2008, that a preferred route had been selected and the new route would be named theWindsor–Essex Parkway.^[173]The below-grade route has six through-lanes and follows Huron Church Road from the former end of Highway 401 to the E. C. Row Expressway, which it then follows alongside to near the border.^[174]Construction began in August 2011,^[175]It was partially opened on June 28, 2015,^[176]and completed to theOjibway Parkway on November 21,^[177][178]TheGordie Howe International Bridge is scheduled for completionin 2025^{[needs update]}, and will tie Highway 401 in withInterstate 75 inDetroit.^[179][180]

The current proposals by theMTO consist of two new freeways in theGTA and continued widening and four-laning of existing highways.Highway 413 is a proposed four-to-six lane freeway bypass of the GTA aroundBrampton, connecting Highway 401 and Highway 407 with Highway 400 north of Vaughan. The 52-kilometre (32 mi) route would include extensions of Highway 410 and Highway 427 as well as a right-of-way for atransitway; the highway has attracted considerable attention, with opinions divided over the benefits of shorter travel times versus irreversible environmental impacts andurban sprawl.^{[181][182][183]}TheBradford Bypass is a proposed four lane rural freeway connecting Highway 400 and Highway 404 north ofBradford and Newmarket.^[184]Like Highway 413, it has attracted criticism for its environmental impact,^[185][186]though it has the support of adjacent municipalities.^[187][188]Preliminary construction works for the route are underway as of 2022.^[189]

While planning for the twinning of Highway 11/17 between Thunder Bay andNipigon began in 1989,^[190]construction did not begin until 2009.^[191]As of 2022, 55 kilometres (34 mi) of two-laned highway remains to be twinned or bypassed, almost all of which is in the engineering phase.^[192]The four-laning of the remaining 68-kilometre (42 mi) gap of Highway 69 has been promised by multiple governments, but no timeline for completion has been announced as of 2022.^[193]

• List of Ontario provincial highways

• Berchem, F.R. (1977).The Yonge Street Story: 1793–1860. McGraw-Hill Ryerson.ISBN 0-07-082567-X.
• Bradford, Robert (2015).Keeping Ontario Moving: The History of Roads and Road Building in Ontario. Dundurn Press.ISBN 978-1-4597-2412-9.
• Brown, Ron (1997).Toronto's Lost Villages. Toronto: Polar Bear Press.ISBN 978-1-896757-02-5.
• Legislative Assembly of Ontario (1896).Appendix to the Report of the Ontario Bureau of Industries. RetrievedMarch 28, 2021.
• Legislative Assembly of Ontario (1897).Report of the Provincial Instructor in Road-Making. Ontario Department of Agriculture. RetrievedMarch 28, 2021.
• A.A.D.T. Traffic Volumes 1955–1969 And Traffic Collision Data 1967–1969. Ontario Department of Highways. 1970.
• Shragge, John; Bagnato, Sharon (1984).From Footpaths to Freeways. Historical Committee, Ministry of Transportation and Communications.ISBN 978-0-7743-9388-1.
• Stamp, Robert M. (1987).QEW – Canada's First Superhighway. The Boston Mills Press.ISBN 0-919783-84-8.

Wikimedia Commons has media related toHighways in Ontario.

• Ministry of Transportation of Ontario (MTO)
• MTO 100th Anniversary - History
• Official Ontario road map
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• Ontario's Highway Programs
• Road maps of Ontario, 1923–2010

• Ontario provincial highways
• Lists of roads in Ontario
• 1920 establishments in Ontario

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