Why are USGS topographic maps called “quadrangles”?
In the making of topographic maps, the USGS subdivides the United States by using Latitude and Longitude lines to form the boundaries of four-sided figures called “quadrangles”. The maps are often referred to as quadrangle maps (or quad maps).
Different sizes of quadrangles have been used over time, for example the 30-minute quadrangle (30 minutes of latitude or longitude on each side) and the 15-minute quadrangle (15 minutes of latitude or longitude on each side). Since 1947, the primary USGS topographic map size has been the 7.5-minute quadrangle, so each side of the map is bound by 7.5 minutes of latitude and 7.5-minutes of longitude.
USGS 7.5-minute topographic maps covering the contiguous 48 states and Hawaii are published at a scale of 1:24,000, meaning that one inch on the map equals 24,000 inches (2,000 feet) on the ground.
In common use, all of the following terms mean the same thing:
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USGS quadrangle map
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quad map
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7.5-minute quadrangle (or quad or map)
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1:24,000 quadrangle (or quad or map)
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24K quadrangle (or quad or map)
The same would not be true for topographic maps of Alaska. Alaska’s 7.5-minute maps are published at a scale of 1:25,000 (one inch on the map equals 25,000 inches on the ground), so they’re sometimes referred to as 1:25,000 maps or 25K maps.
Learn more:
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Maps for America: cartographic products of the USGS and others
Related
What is a digital orthophoto quadrangle (DOQ) or orthoimage?
A digital orthophoto quadrangle (DOQ)--or any orthoimage--is a computer-generated image of an aerial photograph in which displacements (distortions) caused by terrain relief and camera tilts have been removed. It combines the image characteristics of a photograph with the geometric qualities of a map. Unlike an aerial photograph, an orthoimage has a uniform scale, so it can be used as a base map...
Where can I find a topographic map symbol sheet?
Like topographic maps, topographic map symbols have evolved over time. There is no single document that describes all of the symbols used on all USGS topographic maps since they were first created. Maps published 2013-present : US Topo maps have a symbol sheet attached to the map file (PDF format only). Open the PDF file in Adobe Acrobat and click on the paperclip icon. Maps published 1947-2009...
How do I find, download, or order topographic maps?
The U.S. Geological Survey (USGS) has been the primary civilian mapping agency of the United States since 1879. Some of the most well-known USGS maps are the 1:24,000-scale topographic maps, also called 7.5-minute quadrangles . In 2009, the USGS transitioned from our hand scribed historical topographic maps to US Topos , which are computer-generated on a regular schedule using national databases...
Where can I find indexes of USGS topographic maps?
View map indexes on these interactive maps (you must zoom in to see the index lines and map names) : Map Locator on the USGS Store - Click the icon on the left that looks like two pieces of paper and select “1:24,000” for our standard map series. TopoView - Click on any of the round map scale indicators on the right side of the map. The National Map Viewer - Click on the Layer List icon at the top...
What is a topographic map?
The distinctive characteristic of a topographic map is the use of elevation contour lines to show the shape of the Earth's surface. Elevation contours are imaginary lines connecting points having the same elevation on the surface of the land above or below a reference surface, which is usually mean sea level. Contours make it possible to show the height and shape of mountains, the depths of the...
How are U.S. Geological Survey topographic maps named?
A USGS topographic map is usually named for the most prominent feature within the bounds of the map, frequently a community. Most topographic maps are named for the most centrally located, well-known, and/or largest community labeled on the map. If the community for which the map should be named falls on two or more maps, a directional term might be used such as East and West. An example is...
When was the 1:24,000-scale topographic map series for the United States and its territories completed?
The U.S. Geological Survey (USGS) was created in 1879 and published it’s first topographic map in 1882. Systematic topographic mapping was authorized by Congress in 1884. Although 1:24,000-scale topographic maps were produced by the USGS as early as 1904, a formal program to provide primary topographic map coverage at that scale for the entire conterminous United States did not begin until 1947...
Related
What is a digital orthophoto quadrangle (DOQ) or orthoimage?
A digital orthophoto quadrangle (DOQ)--or any orthoimage--is a computer-generated image of an aerial photograph in which displacements (distortions) caused by terrain relief and camera tilts have been removed. It combines the image characteristics of a photograph with the geometric qualities of a map. Unlike an aerial photograph, an orthoimage has a uniform scale, so it can be used as a base map...
Where can I find a topographic map symbol sheet?
Like topographic maps, topographic map symbols have evolved over time. There is no single document that describes all of the symbols used on all USGS topographic maps since they were first created. Maps published 2013-present : US Topo maps have a symbol sheet attached to the map file (PDF format only). Open the PDF file in Adobe Acrobat and click on the paperclip icon. Maps published 1947-2009...
How do I find, download, or order topographic maps?
The U.S. Geological Survey (USGS) has been the primary civilian mapping agency of the United States since 1879. Some of the most well-known USGS maps are the 1:24,000-scale topographic maps, also called 7.5-minute quadrangles . In 2009, the USGS transitioned from our hand scribed historical topographic maps to US Topos , which are computer-generated on a regular schedule using national databases...
Where can I find indexes of USGS topographic maps?
View map indexes on these interactive maps (you must zoom in to see the index lines and map names) : Map Locator on the USGS Store - Click the icon on the left that looks like two pieces of paper and select “1:24,000” for our standard map series. TopoView - Click on any of the round map scale indicators on the right side of the map. The National Map Viewer - Click on the Layer List icon at the top...
What is a topographic map?
The distinctive characteristic of a topographic map is the use of elevation contour lines to show the shape of the Earth's surface. Elevation contours are imaginary lines connecting points having the same elevation on the surface of the land above or below a reference surface, which is usually mean sea level. Contours make it possible to show the height and shape of mountains, the depths of the...
How are U.S. Geological Survey topographic maps named?
A USGS topographic map is usually named for the most prominent feature within the bounds of the map, frequently a community. Most topographic maps are named for the most centrally located, well-known, and/or largest community labeled on the map. If the community for which the map should be named falls on two or more maps, a directional term might be used such as East and West. An example is...
When was the 1:24,000-scale topographic map series for the United States and its territories completed?
The U.S. Geological Survey (USGS) was created in 1879 and published it’s first topographic map in 1882. Systematic topographic mapping was authorized by Congress in 1884. Although 1:24,000-scale topographic maps were produced by the USGS as early as 1904, a formal program to provide primary topographic map coverage at that scale for the entire conterminous United States did not begin until 1947...