For more information, please see the Ontario page from Library and Archives Canada part of www.collectionscanada.gc.ca
Also see Wikipedia:Ontario
Natural Resources Canada has a range of maps, see http://atlas.nrcan.gc.ca/site/english/index.html
Province of Quebec is to the east, whilst the south eastern boundary is Lake Ontario with the US state of New York on the opposite shore and Lake Erie with the US States of Pennsylvania and Ohio opposite. To the south, the boundary runs through Lakes Huron and Superior, with the US State of Michigan opposite. The southern boundary continues with the US State of Minnesota and to the west lies the Province of Manitoba.
Ontario GenWeb has a list of counties & districts and links to historical maps at http://www.rootsweb.ancestry.com/~canon/research-topic-land-maps.html