<P> Prior to the development of the Universal Transverse Mercator coordinate system, several European nations demonstrated the utility of grid - based conformal maps by mapping their territory during the interwar period . Calculating the distance between two points on these maps could be performed more easily in the field (using the Pythagorean theorem) than was possible using the trigonometric formulas required under the graticule - based system of latitude and longitude . In the post-war years, these concepts were extended into the Universal Transverse Mercator / Universal Polar Stereographic (UTM / UPS) coordinate system, which is a global (or universal) system of grid - based maps . </P> <P> The transverse Mercator projection is a variant of the Mercator projection, which was originally developed by the Flemish geographer and cartographer Gerardus Mercator, in 1570 . This projection is conformal, which means it preserves angles and therefore shapes across small regions . However, it distorts distance and area . </P> <P> The UTM system divides the Earth into 60 zones, each 6 ° of longitude in width . Zone 1 covers longitude 180 ° to 174 ° W; zone numbering increases eastward to zone 60, which covers longitude 174 ° E to 180 ° . The polar regions south of 80 ° S and north of 84 ° N are excluded . </P> <P> Each of the 60 zones uses a transverse Mercator projection that can map a region of large north - south extent with low distortion . By using narrow zones of 6 ° of longitude (up to 668 km) in width, and reducing the scale factor along the central meridian to 0.9996 (a reduction of 1: 2500), the amount of distortion is held below 1 part in 1,000 inside each zone . Distortion of scale increases to 1.0010 at the zone boundaries along the equator . </P>

Each utm zone covers how many degrees of longitude wide
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