Map of Upper Canada's Districts
As part of the 1763 Treaty of Paris which ended the Seven Years' War global conflict and the French and Indian War in North America, Great Britain retained control over the former New France, which had been defeated in the French and Indian War. The British had won control after Fort Niagara had surrendered in 1759 and Montreal capitulated in 1760, and the British under Robert Rogers took formal control of the Great Lakes region in 1760. Fort Michilimackinac was occupied by Roger's forces in 1761.
The territories of contemporary southern Ontario and southern Quebec were initially maintained as the single Province of Quebec, as it had been under the French. From 1763 to 1791, the Province of Quebec maintained its French language, cultural behavioural expectations, practices and laws. The British passed the Quebec Act in 1774, which expanded the Quebec colony's authority to include part of the Indian Reserve to the west (i.e., parts of southern Ontario), and other western territories south of the Great Lakes including much of what would become the United States' Northwest Territory, including the modern states of Illinois, Indiana, Michigan, Ohio, Wisconsin and parts of Minnesota.
After the American War of Independence ended in 1783, Britain retained control of the area north of the Ohio River. The official boundaries remained undefined until 1795 and the Jay Treaty. The British authorities encouraged the movement of people to this area from the United States, offering free land to encourage population growth. For settlers, the head of the family received 100 acres (40 ha) and 50 acres (20 ha) per family member, and soldiers received larger grants. These settlers are known as United Empire Loyalists and were primarily English-speaking Protestants. The first townships (Royal and Cataraqui) along the St. Lawrence and eastern Lake Ontario were laid out in 1784, populated mainly with decommissioned soldiers and their families.
"Upper Canada" became a political entity on 26 December 1791 with the Parliament of Great Britain's passage of the Constitutional Act of 1791. The act divided the Province of Quebec into Upper and Lower Canada, but did not yet specify official borders for Upper Canada. The division was effected so that Loyalist American settlers and British immigrants in Upper Canada could have English laws and institutions, and the French-speaking population of Lower Canada could maintain French civil law and the Catholic religion. The first lieutenant-governor was John Graves Simcoe.
The 1795 Jay Treaty officially set the borders between British North America and the United States north to the Great Lakes and St. Lawrence River. On 1 February 1796, the capital of Upper Canada was moved from Newark (now Niagara-on-the-Lake) to York (now Toronto), which was judged to be less vulnerable to attack by the Americans.
The Act of Union 1840, passed 23 July 1840 by the British Parliament and proclaimed by the Crown on 10 February 1841, merged Upper Canada with Lower Canada to form the short-lived United Province of Canada.