Because the Earth is a sphere, any representation of it on a flat surface involves distortion. This distortion is not important for maps showing small parts of the Earth, such as city maps, but quite considerable for maps representing a country or entire continents. The UTM Grid – Map Projections section describes the different systems that can be used to locate any place in Canada.
The decision facing a map-maker, therefore, is not whether to have a distortion on a map, but what type of distortion. Over the centuries, various geometrical schemes have been worked out for representing the curved surface of the Earth on map sheets; these schemes are known as map projections. All projections have certain advantages and disadvantages, and the selection of one or the other depends chiefly on the needs of the user.
The Canada Centre for Mapping and Earth Observation (CCMEO) uses the Universal Transverse Mercator Projection for mapping of the National Topographic System (NTS) series at 1:50 000 and 1:250 000 scales.
This material updated from The Universal Transverse Mercator Grid, Department of Energy, Mines and Resources Canada, Surveys and Mapping Branch, Ottawa, © 1969, The Queen's Printer.