A map provides us with a view or representation of things here on Earth. Topographic maps are one of the most widely used of all maps. The wide range of information provided by topographic maps make them extremely useful to professional and recreational map users alike.

The distinguishing feature of the topographic map is its' use of contour lines to show the shape and elevation of the land. Contours are imaginary lines that join points of equal elevation on the surface of the land above or below a reference surface such as mean sea level (the average height of the surface of the sea for all stages of the tide; used as a reference for elevations). Contours allow us to measure the height of mountains, depths of the ocean bottom and the steepness of slopes.

Topographic maps depict natural occurrences such as mountains, streams, valleys, plains and vegetation. They also include manmade features such as roads, boundaries, and buildings.

The U.S. Geological Survey (USGS) is responsible for topographic and geologic mapping in the United States. They began in 1879 by mapping the largely uninhabited areas of the West.

Travel was difficult and mapping instruments crude for the first mapping pioneers. They traveled to many locations by pack mule train that could not be reached otherwise. Most of the maps were created using a classic mapping technique called planetable surveying.

Planetable surveying involved great skill and sometimes, great daring. The topographer would climb to the area's best vantage point carrying his planetable - a portable drawing board on a tripod with a sighting device - and from there, would carefully plot on the map those features that could be seen and measured in the field. This type of surveying was used until the 1940's when the airplane and the age of photogrammetry (the science of obtaining reliable information by measuring and interpreting photographs) took its' place.

Aerial photography brought a new era to mapmaking. Aerial photographs were first used in the 1930's when the USGS assisted the Tennessee Valley Authority in mapping its area of responsibility. This was the first full-scale test of the use of aerial photographs in creating maps. The test was successfull and the use of aerial photos increased.

Yes. Most USGS topographic maps use brown contours to show the shape and elevation of the terrain. Contour intervals vary, depending on the type of terrain and the scale of the map.

Maps at scales of 1:24,000 (l inch = 2,000 feet) show a detailed area. These maps are useful for engineering, local area planning and recreational purposes.

Maps at scales of 1:250,000 (l inch = about 4 miles) or 1:500,000 (l inch = about 8 miles), cover very large areas on each sheet and are useful in regional and statewide planning.

Most USGS map series divide the U.S. into quadrangles bounded by two lines of latitude and two lines of longitude (a 7.5 minute map shows an area that spans 7.5 minutes of latitude and 7.5 minutes of longitude). Maps are usually named after the most prominent feature in the quadrangle. Other maps show a whole area such as a county, State, or place of interest.

Types of Topographic Maps