General Map Information

Map Formats

Maps are available in either flat or folded formats, with generally the same information on either format. Most maps are produced folded, with only those called "wall maps" left flat by the publisher. If you want a map for on the wall, and a flat version is not available, your best bet is to have a folded map laminated. This flattens the map nicely although the fold lines are still somewhat visible.

To take the curl out of a rolled map, in order to lay it flat or mount it on a wall: reverse the roll by rolling the map backwards against the roll) and holding it with a rubber band for a while. The stiffer the map material, the longer it will take to reverse the roll of the map and flatten it out. (This process could be called "roll reversal.")

Map Legend

Each map features a legend, or key, which explains the meaning of a map´s symbols. The legend will distinguish particular types of lines, showing that they depict rivers, roads, railroads, or political boundaries. The legend indicates how cities are depicted with squares or dots, according to their sizes. It also illustrates the use of color to show different elevations and political entities.

The map legend also provides some or all of the following important information about a map: its title, scale, projection, cartographer, publisher, date of compilation, and date of printing.

Map Projection

Projection is a mathematical formula that allows one to depict information about the curved, 3-dimensional surface of the Earth onto a flat, 2-dimensional piece of paper. The systematic drawing of lines on a plane surface to represent the earth's parallels of latitude and the meridians of longitude is a convenient means of illustrating projection.

A map projection may be established by analytical computation or may be constructed geometrically. There are many projections; some of the many possible examples are Mercator, Albers, Robinson, Peters, and Van Der Grinten. Each projection gives the map reader a unique perspective on the arrangement of the continents and oceans.

Any map is a subjective generalization. It cannot show everything that is actually there, no matter how large the scale, thus in a sense it is also a subjective document, reflecting the objectives or political orientation of the mapmaker.

Map Scale

Of critical importance to any map is the scale. Scale is the ratio between the distance between two points on a map and the actual distance it represents. Example: 1:50,000 means 1 inch on the map equals 50,000 inches on the ground. Or for that matter one whatever (thumb width, foot, metre) equals 50,000 of the same on the ground.

When you hear someone refer to a "large-scale" map, they are referring to one in which a given detail is shown larger. Generally speaking, "large scale" refers to maps under 1:50,000, and are the best source for detailed local information. "Intermediate-scale" maps range from 1:50,000 to 1:100,000, and are especially useful for land management and regional planning. "Small-scale" maps go from 1:250,000 on up, and are best for overviews of entire countries or continents.