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Maps, Atlases, & Gazetteers

General Information

Types of Maps

Aerial maps are produced using aerial photography or remote sensing satelite imagery.

Climate maps give information about the climate and precipitation of a region, often by using colors to show climate or precipitation zones.

Economic maps feature economic activity in an area. Symbols may be used to show the locations or extent of economic activities.

Geologic maps show the distribution of geologic features, including different kinds of rocks and faults, usually printed on top of a regular map (called a base map). The geology is represented by colors, lines, and special symbols unique to geologic maps. The USGS has information on colors and symbols used on geologic maps.

Historic maps are useful to historians, environmentalists, genealogists, and others interested in researching the background of a particular area.

Hydrologic maps show water-resources information, such as depth to ground water, floods, irrigated acreage, aquifers, water availability, surface-water discharge, chemical or mineral content of water, surface impoundments, and water temperature.

Physical maps illustrate the physical features of an area, such as the mountains, rivers and lakes. Colors may be used to show relief-differences in land elevations. 

Political maps indicate state and national boundaries and capital and major cities.

Resource maps show natural resources in an area, often using symbols or colors to show the locations of natural resources.

Road or highway maps show highways and roads, cities, and often other points of interest in an area.

Satellite image maps are multicolor or black-and-white photograph-like maps made from data collected by Earth resources satellites.

Shaded-relief maps accentuate physiographic features of special interest using relief shading that simulates the appearance of sunlight and shadows on the terrain and creates the illusion of three-dimensional topography.

Thematic maps feature special subjects such as population, temperature, soils, hazards, vegetation, etc.

Topographic maps show the topography (shape and elevation) and features of an area on the earth's surface, using contour lines and symbols. See the USGS webpage Topographic Map Symbols(link is external) for more information.


Map Scale

Scale is the relationship between distance on the map and distance on the ground. A map scale usually is given as a fraction or a ratio such as 1/10,000 or 1:10,000which means 1 unit of measurement on the map—1 inch or 1 centimeter—represents 10,000 of the same units on the ground. If the scale were 1:63,360, then 1 inch on the map would represent 63,360 inches, or 1 mile, on the ground (63,360 inches divided by 12 inches equals 5,280 feet, or 1 mile). The first number (map distance) is always 1. The second number (ground distance) is different for each scale; the larger the second number is, the smaller the scale of the map.

An information sheet from the U.S. Geological Survey gives more detail on scale.

Map Projections

A map projection is used to portray all or part of the round Earth on a flat surface, which cannot be done without some distortion. Mapmakers have devised a number of ways to project the image of the globe onto paper.

Every flat map misrepresents the surface of the Earth in some way. No map can rival a globe in truly representing the surface of the entire Earth. However, a map or parts of a map can show one or more — but never all — of the following: True directions. True distances. True areas. True shapes.

The degree and kinds of distortion vary with the projection used in making a map of a particular area. Some projections are suited for mapping large areas that are mainly north-south in extent, others for large areas that are mainly east-west in extent, and still others for large areas that are oblique to the Equator. The mapmaker must select the projection best suited to a specific map.

GIS (Geographic Information Systems)

Geographic information system (GIS) technology can be used for scientific investigations, resource management, and development planning. For example, a GIS might allow emergency planners to easily calculate emergency response times in the event of a natural disaster, or a GIS might be used to find wetlands that need protection from pollution.


Topographic Maps

This map series divides the United States into quadrangles bounded by two lines that span either 7.5 or 15 minutes of latitude and  longitude. The scale of 1:24,000 (1 inch = 2,000 feet) shows an area in detail, useful for engineering, local area planning, and recreational purposes such as hiking or hunting. Contour lines show the shape and elevation of the terrain. The maps also show and name prominent natural and cultural features. For more information, see Topographic Map Symbols.

A set of topographic maps is available in the library storage annex. The USGS no longer prints or distributes topographic maps to libraries, so those in our print collection are not be the most recent version. The USGS provides digital topographic maps that are available free of charge; follow the steps on the digital topographic maps locator page to download your map. You'll also have an option to order a print copy of the map (for a fee). This site also contains scans of many of the historic topographic maps daying back to the 1880's.

Records of the topographic maps available in the library storage annex may be viewed in the online catalog. Use our pull service or the request button in the online catalog to have the maps you need delivered to one of the library locations. Be sure to check holdings for both states for maps that cross state borders.

Other USGS Map Series

The USGS produces many other map series. These are just a few examples, which can be found in the Government Documents shelving area (northwest corner of the 2nd floor).

Circum-Pacific (CP) Map Series I 19.91/2:
Coal Investigations (C) I 19.85:
Geologic Investigations (I) I 19.91:
Geologic Quadrangle (GQ) I 19.88:
Geophysical Investigations (GP) I 19.87:
Hydrologic Investigations Atlases (HA) I 19.89:
Hydrologic Unit Map (I) 19.89/2:
Land Use and Cover (L) I 19.112:
Mineral Investigations (MR) I 19.90:
Miscellaneous Field Studies (MF) I 19.113:
Miscellaneous Investigations Studies (I) I 19.91:
Oil and Gas Investigations Charts (OC) I 19.92:
Oil and Gas Investigations Maps (OM) I 19.93:
Scientific Investigations Maps (SIM) I 19.91/3:

Links to Maps

Last updated: 8/10/2016