Northwestern Ontario is the region within the Canadian province of Ontario which lies north and west of Lake Superior, and west of Hudson Bay and James Bay. It includes most of subarctic Ontario. Its western boundary is the Canadian province of Manitoba, which disputed Ontario's claim to the western part of the region. 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. In 1912 the Parliament of Canada by the Ontario Boundaries Extension Act gave jurisdiction over the District of Patricia to Ontario, thereby extending the northern boundary of the province to Hudson Bay.

It is the province's most sparsely populated region. Its only major city is Thunder Bay. Smaller communities in the region include Kenora, Dryden, Rainy River, Atikokan , Fort Frances, Sioux Lookout and Central Patricia.

Northwestern Ontario consists of Kenora District, Rainy River District and Thunder Bay District.

Population

• 2003 Postcensal estimate 243,256
  • Kenora District 66,130
  • Rainy River District 22,343
  • Thunder Bay District 154,783

For more information, see Northern Ontario.