Ontario is Canada's most populous and economically powerful province. It's capital, Toronto, has a population of over 2 1/2 million people, and is Canada's financial center. As Canada has the 13th largest economy in the world, that translates into considerable economic concentration in that one province.
In addition to Ontario's role as a major financial center, the province benefits economically from its manufacturing base, which includes automotive parts, electrical machinery and equipment, and mechanical appliances. Ontario also has a mining industry that produces gold, copper, platinum, nickel, lime, and gypsum. Ontario's mining industry was a relatively late development in the country's history due to the difficulty of extracting minerals from its difficult terrain, especially during its long winters. As the center of Canada's economy, Ontario also benefits considerably from the country's energy sector, especially its vast oil sand reserves concentrated in Alberta province, the financing of which goes through Toronto. In fact, as Canada's economic center, the country's tremendous oil reserves, among the largest in the world, account for a considerable proportion of the total wealth that traverses Ontario's economy.
Ontario's largest single economic sector, however, remains the service industry, lead by finance, insurance, real estate, trade, and health care. [See www.fin.gov.on.ca/en/economy/]