All maps have to be “projected” to appear on a flat screen or piece of paper. The earth is an “oblate spheroid”, a sphere that is thicker around it’s equator then the poles. Simply just drawing a map to the latitude and longitude, leads to a rather distorted looking maps.

There are two common systems of representing the cylindrical globe on maps: the Normal Meractor and the Universal Transverse Mercator. Most topographic maps are projected as Universal Transverse Mercator, as it’s very accurate for shapes, sizes, and distances, as it reflects the natural curvature of the earth’s “oblate spheroid” over smaller distances on a flat surface.

There is one big problem with Universal Transverse Mercator, is that it distorts cardinal directions, especially as distance grows. Simply said, a straight westerly line, such as the 42 degrees latitude line that marks the southern border between Pennsylvania and New York, is bent northwards to keep shape and proportion of NY State correct, based on the “oblate spheriod” of earth. If you want pure north and south lines over a distance, then you have no choice but to use Normal Mercator.

So what do you prefer? I tend to prefer the UTM, as it’s more accurate for everything but direction over long distances, giving one an accurate overview of an area. It also makes for some pretty stylistic looking NY State Maps, and keeps similarly sized areas of right size, rather then stretched too large.