Paleo-Indians were the first people to settle on the lands of Ontario, arriving there after the Laurentide Ice Sheet melted roughly 11,000 years ago. From them, many ethnocultural groups emerged and came to exist on the lands of Ontario: the Algonquins, Mississaugas, Ojibway, Cree, Odawa, Pottowatomi, and Iroquois.
In the 15th century, the Byzantine Empire fell, prompting Western Europeans to search for new sea routes to the Far East. Around 1522–1523, Giovanni da Verrazzano persuaded King Francis I of France to commission an expedition to find a western route to Cathay (China) via a Northwest Passage. Though this expedition was unsuccessful, it established the name "New France" for northeastern North America. After a few expeditions, France mostly abandoned North America for 50 years because of its financial crisis; France was involved in the Italian Wars and there were religious wars between Protestants and Catholics. Around 1580 however, the rise of the fur trade (particularly the demand for beaver pelts), reignited French interest.
In 1608, Samuel de Champlain established France's first colonial settlement in New France, the Habitation de Québec (now Quebec City), in the colony of Canada (now southern Quebec). Afterwards, French explorers continued to travel west, establishing new villages along the coasts of the Saint Lawrence River. French explorers, the first of which was Étienne Brûlé who explored the Georgian Bay area in 1610–1612, mapped Southern Ontario and called the region the Pays d'en Haut ("Upper Country"), in reference to the region being upstream of the Saint Lawrence River. The colony of the Pays d'en Haut was formally established in 1610 as an administrative dependency of Canada, and was for defence and business rather than a settlement colony. The territory of the Pays-d'en-Haut was quite large and would today include the province of Ontario, as well as, in whole or in part, the American states of Minnesota, Wisconsin, Illinois, Indiana, Michigan, Ohio, Pennsylvania and New York. Indigenous peoples were the vast majority of the Pays d'en Haut population.
As for Northern Ontario, the English explorer Henry Hudson sailed into Hudson Bay in 1611 and claimed its drainage basin for England. The area would become known as Rupert's Land.
Samuel de Champlain reached Lake Huron in 1615, and French missionaries, such as the Jésuites and Supliciens, began to establish posts along the Great Lakes. The French allied with most Indigenous groups of Ontario, all for the fur trade and for defence against Iroquois attacks (which would later be called the Iroquois Wars). The French would declare their Indigenous allies to be subjects of the King of France and would often act as mediators between different groups. The Iroquois later allied themselves with the British.
From 1634 to 1640, the Huron were devastated by European infectious diseases, such as measles and smallpox, to which they had no immunity. By 1700, the Iroquois had been driven out or left the area that would become Ontario and the Mississaugas of the Ojibwa had settled the north shore of Lake Ontario. The remaining Huron settled north of Quebec.
During the French and Indian War, the North American theater of the Seven Years' War of 1754 to 1763, the British defeated the armies of New France and its Indigenous allies. In the Treaty of Paris 1763 France ceded most of its possessions in North America to Britain. Using the Quebec Act, Britain re-organised the territory into the Province of Quebec.
In 1782–1784, 5,000 United Empire Loyalists entered what is now Ontario following the American Revolution. The Kingdom of Great Britain granted them 200 acres (81 ha) land and other items with which to rebuild their lives. The British also set up reserves in Ontario for the Mohawks who had fought for the British and had lost their land in New York state. Other Iroquois, also displaced from New York were resettled in 1784 at the Six Nations reserve at the west end of Lake Ontario. The Mississaugas, displaced by European settlements, would later move to Six Nations also.
After the American War of Independence, the first reserves for First Nations were established. These are situated at Six Nations (1784), Tyendinaga (1793) and Akwesasne (1795). Six Nations and Tyendinaga were established by the British for those Indigenous groups who had fought on the side of the British, and were expelled from the new United States. Akwesasne was a pre-existing Mohawk community and its borders were formalized under the 1795 Jay Treaty.
In 1788, while part of the province of Quebec, southern Ontario was divided into four districts: Hesse, Lunenburg, Mecklenburg, and Nassau. In 1792, the four districts were renamed: Hesse became the Western District, Lunenburg became the Eastern District, Mecklenburg became the Midland District, and Nassau became the Home District. Counties were created within the districts.
The population of Canada west of the St. Lawrence-Ottawa River confluence substantially increased during this period, a fact recognized by the Constitutional Act of 1791, which split Quebec into the Canadas: Upper Canada southwest of the St. Lawrence-Ottawa River confluence, and Lower Canada east of it.
John Graves Simcoe was appointed Upper Canada's first Lieutenant governor in 1793. A second wave of Americans, not all of them necessarily loyalists moved to Upper Canada after 1790 until the pre-war of 1812, many seeking available cheap land, and at the time, lower taxation.
By 1798, there were eight districts: Eastern, Home, Johnstown, London, Midland, Newcastle, Niagara, and Western. By 1826, there were eleven districts: Bathurst, Eastern, Gore, Home, Johnstown, London, Midland, Newcastle, Niagara, Ottawa, and Western. By 1838, there were twenty districts: Bathurst, Brock, Colbourne, Dalhousie, Eastern, Gore, Home, Huron, Johnstown, London, Midland, Newcastle, Niagara, Ottawa, Prince Edward, Simcoe, Talbot, Victoria, Wellington, and Western.
American troops in the War of 1812 invaded Upper Canada across the Niagara River and the Detroit River, but were defeated and pushed back by the British, Canadian fencibles and militias, and First Nations warriors. However, the Americans eventually gained control of Lake Erie and Lake Ontario. The 1813 Battle of York saw American troops defeat the garrison at the Upper Canada capital of York. The Americans looted the town and burned the Upper Canada Parliament Buildings during their brief occupation. The British would burn the American capital of Washington, D.C. in 1814.
After the War of 1812, relative stability allowed for increasing numbers of immigrants to arrive from Europe rather than from the United States. As was the case in the previous decades, this immigration shift was encouraged by the colonial leaders. Despite affordable and often free land, many arriving newcomers, mostly from Britain and Ireland, found frontier life with the harsh climate difficult, and some of those with the means eventually returned home or went south. However, population growth far exceeded emigration in the following decades. It was a mostly agrarian-based society, but canal projects and a new network of plank roads spurred greater trade within the colony and with the United States, thereby improving previously damaged relations over time.
Meanwhile, Ontario's numerous waterways aided travel and transportation into the interior and supplied water power for development. As the population increased, so did the industries and transportation networks, which in turn led to further development. By the end of the century, Ontario vied with Quebec as the nation's leader in terms of growth in population, industry, arts and communications.
Unrest in the colony began to chafe against the aristocratic Family Compact who governed while benefiting economically from the region's resources, and who did not allow elected bodies power. This resentment spurred republican ideals and sowed the seeds for early Canadian nationalism. Accordingly, rebellion in favour of responsible government rose in both regions; Louis-Joseph Papineau led the Lower Canada Rebellion and William Lyon Mackenzie, first Toronto mayor, led the Upper Canada Rebellion. In Upper Canada, the rebellion was quickly a failure. William Lyon Mackenzie escaped to the United States, where he declared the Republic of Canada on Navy Island on the Niagara River.
Although both rebellions were put down in short order, the British government sent Lord Durham to investigate the causes. He recommended self-government be granted and Lower and Upper Canada be re-joined in an attempt to assimilate the French Canadians. Accordingly, the two colonies were merged into the Province of Canada by the Act of Union 1840, with the capital at Kingston, and Upper Canada becoming known as Canada West. Parliamentary self-government was granted in 1848. There were heavy waves of immigration in the 1840s, and the population of Canada West more than doubled by 1851 over the previous decade. As a result, for the first time, the English-speaking population of Canada West surpassed the French-speaking population of Canada East, tilting the representative balance of power.
In 1849, the districts of southern Ontario were abolished by the Province of Canada, and county governments took over certain municipal responsibilities. The Province of Canada also began creating districts in sparsely populated Northern Ontario with the establishment of Algoma District and Nipissing District in 1858.
An economic boom in the 1850s coincided with railway expansion across the province, further increasing the economic strength of Central Canada. With the repeal of the Corn Laws and a reciprocity agreement in place with the United States, various industries such as timber, mining, farming and alcohol distilling benefited tremendously.
A political stalemate between the French- and English-speaking legislators, as well as fear of aggression from the United States during and immediately after the American Civil War, led the political elite to hold a series of conferences in the 1860s to effect a broader federal union of all British North American colonies. The British North America Act took effect on July 1, 1867, establishing the Dominion of Canada, initially with four provinces: Nova Scotia, New Brunswick, Quebec and Ontario. The Province of Canada was divided into Ontario and Quebec so that each linguistic group would have its own province. Both Quebec and Ontario were required by section 93 of the British North America Act to safeguard existing educational rights and privileges of the Protestant and Catholic minorities. Thus, separate Catholic schools and school boards were permitted in Ontario. However, neither province had a constitutional requirement to protect its French- or English-speaking minority. Toronto was formally established as Ontario's provincial capital.
The borders of Ontario, its new name in 1867, were provisionally expanded north and west. When the Province of Canada was formed, its borders were not entirely clear, and Ontario claimed eventually to reach all the way to the Rocky Mountains and Arctic Ocean. With Canada's acquisition of Rupert's Land, Ontario was interested in clearly defining its borders, especially since some of the new areas in which it was interested were rapidly growing. After the federal government asked Ontario to pay for construction in the new disputed area, the province asked for an elaboration on its limits, and its boundary was moved north to the 51st parallel north.
Once constituted as a province, Ontario proceeded to assert its economic and legislative power. In 1872, the lawyer Oliver Mowat became Premier of Ontario and remained as premier until 1896. He fought for provincial rights, weakening the power of the federal government in provincial matters, usually through well-argued appeals to the Judicial Committee of the Privy Council. His battles with the federal government greatly decentralized Canada, giving the provinces far more power than John A. Macdonald had intended. He consolidated and expanded Ontario's educational and provincial institutions, created districts in Northern Ontario, and fought to ensure that those parts of Northwestern Ontario not historically part of Upper Canada (the vast areas north and west of the Lake Superior-Hudson Bay watershed, known as the District of Keewatin) would become part of Ontario, a victory embodied in the Canada (Ontario Boundary) Act, 1889. He also presided over the emergence of the province into the economic powerhouse of Canada. Mowat was the creator of what is often called Empire Ontario.
Beginning with Macdonald's National Policy (1879) and the construction of the Canadian Pacific Railway (1875–1885) through Northern Ontario and the Canadian Prairies to British Columbia, Ontario manufacturing and industry flourished. However, population increases slowed after a large recession hit the province in 1893, thus slowing growth drastically but for only a few years. Many newly arrived immigrants and others moved west along the railway to the Prairie Provinces and British Columbia, sparsely settling Northern Ontario.
The northern and western boundaries of Ontario were in dispute after Canadian Confederation. Ontario's right to Northwestern Ontario was determined by the Judicial Committee of the Privy Council in 1884 and confirmed by the Canada (Ontario Boundary) Act, 1889 of the Parliament of the United Kingdom. By 1899, there were seven northern districts: Algoma, Manitoulin, Muskoka, Nipissing, Parry Sound, Rainy River, and Thunder Bay. Four more northern districts were created between 1907 and 1912: Cochrane, Kenora, Sudbury and Timiskaming.
Mineral exploitation accelerated in the late 19th century, leading to the rise of important mining centres in the northeast, such as Sudbury, Cobalt and Timmins. The province harnessed its water power to generate hydro-electric power and created the state-controlled Hydro-Electric Power Commission of Ontario, later Ontario Hydro. The availability of cheap electric power further facilitated the development of industry. The Ford Motor Company of Canada was established in 1904 and the McLaughlin Motor Car Company (later General Motors Canada) was founded in 1907. The motor vehicle industry became the most lucrative industry for the Ontario economy during the 20th century.
In July 1912, the Conservative government of James Whitney issued Regulation 17 which severely limited the availability of French-language schooling to the province's French-speaking minority. French Canadians reacted with outrage, journalist Henri Bourassa denouncing the "Prussians of Ontario". The regulation was eventually repealed in 1927.
Influenced by events in the United States, the government of William Hearst introduced prohibition of alcoholic drinks in 1916 with the passing of the Ontario Temperance Act. However, residents could distil and retain their own personal supply, and liquor producers could continue distillation and export for sale, allowing this already sizeable industry to strengthen further. Ontario became a hotbed for the illegal smuggling of liquor and the biggest supplier into the United States, which was under complete prohibition. Prohibition in Ontario came to an end in 1927 with the establishment of the Liquor Control Board of Ontario under the government of Howard Ferguson. The sale and consumption of liquor, wine, and beer are still controlled by some of the most extreme laws in North America to ensure strict community standards and revenue generation from the alcohol retail monopoly are upheld.
The post-World War II period was one of exceptional prosperity and growth. Ontario has been the recipients of most immigration to Canada, largely immigrants from war-torn Europe in the 1950s and 1960s and following changes in federal immigration law, a massive influx of non-Europeans since the 1970s. From a largely ethnically British province, Ontario has rapidly become culturally very diverse.
The nationalist movement in Quebec, particularly after the election of the Parti Québécois in 1976, contributed to driving many businesses and English-speaking people out of Quebec to Ontario, and as a result, Toronto surpassed Montreal as the largest city and economic centre of Canada. Depressed economic conditions in the Maritime Provinces have also resulted in de-population of those provinces in the 20th century, with heavy migration into Ontario.
Ontario's official language is English, although there exists a number of French-speaking communities across Ontario. French-language services are made available for communities with a sizeable French-speaking population; a service that is ensured under the French Language Services Act of 1989.
The thinly populated Canadian Shield, which dominates the northwestern and central portions of the province, comprises over half the land area of Ontario. Although this area mostly does not support agriculture, it is rich in minerals, partly covered by the Central and Midwestern Canadian Shield forests, and studded with lakes and rivers. Northern Ontario is subdivided into two sub-regions: Northwestern Ontario and Northeastern Ontario.
The virtually unpopulated Hudson Bay Lowlands in the extreme north and northeast are mainly swampy and sparsely forested.
Southern Ontario, which is further sub-divided into four sub-regions: Central Ontario (although not actually the province's geographic centre), Eastern Ontario, Golden Horseshoe and Southwestern Ontario (parts of which were formerly referred to as Western Ontario).
Despite the absence of any mountainous terrain in the province, there are large areas of uplands, particularly within the Canadian Shield which traverses the province from northwest to southeast and also above the Niagara Escarpment which crosses the south. The highest point is Ishpatina Ridge at 693 metres (2,274 ft) above sea level in Temagami, Northeastern Ontario. In the south, elevations of over 500 m (1,640 ft) are surpassed near Collingwood, above the Blue Mountains in the Dundalk Highlands and in hilltops near the Madawaska River in Renfrew County.
The Carolinian forest zone covers most of the southwestern region of the province. The temperate and fertile Great Lakes-Saint Lawrence Valley in the south is part of the Eastern Great Lakes lowland forests ecoregion where the forest has now been largely replaced by agriculture, industrial and urban development. A well-known geographic feature is Niagara Falls, part of the Niagara Escarpment. The Saint Lawrence Seaway allows navigation to and from the Atlantic Ocean as far inland as Thunder Bay in Northwestern Ontario. Northern Ontario covers approximately 87% of the province's surface area; conversely, Southern Ontario contains 94% of the population.
Point Pelee is a peninsula of Lake Erie in southwestern Ontario (near Windsor and Detroit, Michigan) that is the southernmost extent of Canada's mainland. Pelee Island and Middle Island in Lake Erie extend slightly farther. All are south of 42°N – slightly farther south than the northern border of California.
Ontario's climate varies by season and location. Three air sources affect it: cold, dry, arctic air from the north (dominant factor during the winter months, and for a longer part of the year in far northern Ontario); Pacific polar air crossing in from the western Canadian Prairies/US Northern Plains; and warm, moist air from the Gulf of Mexico and the Atlantic Ocean. The effects of these major air masses on temperature and precipitation depend mainly on latitude, proximity to major bodies of water and to a small extent, terrain relief. In general, most of Ontario's climate is classified as humid continental.
Ontario has three main climatic regions:
In the northeastern parts of Ontario, extending south as far as Kirkland Lake, the cold waters of Hudson Bay depress summer temperatures, making it cooler than other locations at similar latitudes. The same is true on the northern shore of Lake Superior, which cools hot, humid air from the south, leading to cooler summer temperatures. Along the eastern shores of Lake Superior and Lake Huron winter temperatures are slightly moderated but come with frequent heavy lake-effect snow squalls that increase seasonal snowfall totals to upwards of 3 m (10 ft) in some places. These regions have higher annual precipitation, in some places over 100 cm (39 in).
Severe thunderstorms peak in summer. Windsor, in Southern (Southwestern) Ontario, has the most lightning strikes per year in Canada, averaging 33 days of thunderstorm activity per year. In a typical year, Ontario averages 11 confirmed tornado touchdowns. However, over the last 4 years,
it has had upwards of 20 tornado touchdowns per year, with the highest frequency in the Windsor-Essex – Chatham Kent area, though few are very destructive (the majority between F0 to F2 on the Fujita scale). Ontario had a record 29 tornadoes in both 2006 and 2009. Tropical depression remnants occasionally bring heavy rains and winds in the south, but are rarely deadly. A notable exception was Hurricane Hazel which struck Southern Ontario centred on Toronto, in October 1954.
In the 2021 census, Ontario had a population of 14,223,942 living in 5,491,201 of its 5,929,250 total dwellings, a 5.8 percent change from its 2016 population of 13,448,494. With a land area of 892,411.76 km (344,562.11 sq mi), it had a population density of 2 (41.3/sq mi) in 2021. The largest population centres in Ontario are Toronto, Ottawa, Hamilton, Kitchener, London and Oshawa, which all have more than 300,000 inhabitants.
The percentages given below add to more than 100 per cent because of dual responses (e.g., "French and Canadian" response generates an entry both in the category "French Canadian" and in the category "Canadian").
The majority of Ontarians are of English or other European descent including large Scottish, Irish and Italian communities. Slightly less than 5 per cent of the population of Ontario is Franco-Ontarian, that is those whose native tongue is French, although those with French ancestry account for 11 per cent of the population. Compared to natural increase or interprovincial migration, immigration is a huge population growth force in Ontario, as it has been over the last two centuries. More recent sources of immigrants with large or growing communities in Ontario include East Asians, South Asians, Caribbeans, Latin Americans, Europeans, and Africans. Most populations have settled in the larger urban centres.
In 2021, 34.3% of the population consisted of visible minorities and 2.9% of the population was Indigenous, mostly of First Nations and Métis descent. There was also a small number of Inuit in the province. The number of Indigenous people and visible minorities has been increasing at a faster rate than the general population of Ontario.
In 2021, 52.1% of the population was Christian, with the largest religious denominations being the Roman Catholic Church (with 26.0% of the population) and the United Church of Canada with (4.1%). Other religions included Islam (6.7%), Hinduism (4.1%). 31.6% of Ontarians had no religious affiliation.
The major religious groups in Ontario in 2021 were:
In Ontario, Catholics are represented by the Assembly of Catholic Bishops of Ontario and the Anglican Protestants by the Ecclesiastical Province of Ontario.
As of the 2021 Canadian Census, the ten most spoken languages in the province included English (13,650,230 or 97.28%), French (1,550,545 or 11.05%), Mandarin (467,420 or 3.33%), Hindi (436,125 or 3.11%), Spanish (401,205 or 2.86%), Punjabi (397,865 or 2.84%), Cantonese (352,135 or 2.51%), Arabic (342,860 or 2.44%), Italian (312,800 or 2.23%), and Urdu (295,175 or 2.1%).[note 3]
The principal language of Ontario is English, the province's de facto official language, with approximately 97.2 per cent of Ontarians having proficiency in the language, although only 69.5 per cent of Ontarians reported English as their mother tongue in the 2016 Census. English is one of two official languages of Canada, with the other being French. English and French are the official languages of the courts in Ontario. Approximately 4.6 per cent of the population identified as francophone,[note 4] and a total of 11.5 per cent of Ontarians reported having proficiency in French. Approximately 11.2 per cent of Ontarians reported being bilingual in both English and French. Approximately 2.5 per cent of Ontarians have no proficiency in either English or French.
Franco-Ontarians are concentrated in the northeastern, eastern, and extreme southern parts of the province, where under the French Language Services Act, provincial government services are required to be available in French if at least 10 per cent of a designated area's population report French as their native language or if an urban centre has at least 5,000 francophones.
Other languages spoken by residents include Arabic, Bengali, Cantonese, Dutch, German, Greek, Gujarati, Hindi, Hebrew, Italian, Korean, Malayalam, Mandarin, Marathi, Persian, Polish, Portuguese, Punjabi, Russian, Sinhalese, Somali, Spanish, Tagalog, Telugu, Tamil, Tibetan, Ukrainian, Urdu, and Vietnamese.