The topographic map has been around since the late 1700s, and has continued to evolve into the extremely detail-oriented maps we see today. Topos were developed through topographical surveys; the information they revealed was compiled and transferred to these special maps to show the features of the relevant terrain.
Topographic maps help all sorts of people plan events and projects that would otherwise require physically inspecting the area. Professional planners looking to construct buildings or whole neighborhoods can use topos to find suitable construction areas. Miners have used them to study specific regions to predict where to dig. Even hikers and bicyclists use topographic maps to plan the best routes.
Topographic maps use symbols and colors to represent different elevations and types of terrain, and to identify large items on the surface of the earth. Contour lines are a very common way to show differences in terrain or elevation, but color also plays a major part. For example, a topographic map may show the United States with red, green and yellow splotches, which could represent, high, middle and low altitudes. These maps are also used to show mountains, large bodies of water (such as lakes, reservoirs, rivers, and streams), large structures and/or local vegetation.
Maps all come with legends, but there are many features specific to topographic maps that are industry-standard, and will read the same on any of them. Sharp, pointed "V" shapes in the contour lines represent stream valleys caused by erosion. "O"-shaped contour lines are generally representative of uphill and downhill terrain; the closer the loops get, the nearer the top of the hill they are. Contours that are close together represent a steep grade or slope, whereas lines spaced farther apart indicate a slighter grade.
These maps play an important part in activity planning. For instance, a motorist wishing to cross the country would not want to simply plan his route by looking at the available roads and picking the shortest travel time. By looking at a topographic map, he can be aware of mountain ranges, rocky areas, river crossings, landmarks and a myriad of other things that can help him make more informed travel decisions.