Contained within the 3rd Edition (1957) of the Atlas of Canada is a map that shows as many populated places in the prairies as the scale of the map will permit. It also indicates, within certain limits, the number of inhabitants at each place according to the 1956 Census of Canada. The map also distinguishes between those places which were incorporated and those which were not. Therefore, it shows the urban municipalities in those parts of the various provinces covered by the map. Traditionally the Prairie Region is considered to consist of Alberta, Saskatchewan and Manitoba yet this map omits much of Alberta and includes part of northwestern Ontario.