Maps were produced by the Department of Militia and Defence (later the Department of National Defence) between 1906 and 1953. The map series provides coverage for parts of the Province of Ontario, with occasional border regions of other provinces, and/or, of the United States. In some cases, information for the American portion of the maps was obtained from the USGS (United States Geological Survey).
Although the features represented were largely standardized from the beginning of the series, there exists greater variations in the appearance of maps up to 1923, when a common set of map specifications was established. Increasing standardization among the various Government Agencies involved also required that all maps were published ungridded; however, the military reserved the right to overprint grids as necessary. This accounts for the presence of gridding on a significant percentage of preserved maps, particularly through the 1930.
**Please note that that the edition number for these maps is assumed based off of publication dates, and that this information is not available in any definitive map list. As a result, the edition number may not be printed on the map, and/or may conflict with other map information. It is provided as a guide to how the map fits in with other publications of this sheet only.**
For more information on the history, production and publication of these maps, see Additional Documentation.