Frequently Asked Questions

Mapping, Remote Sensing, and Geospatial Data

The USGS provides the mapping and digital geospatial foundation for the Nation.

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Image: USGS Topographers at Work
Within the conterminous 48 states, the NAD27-NAD83 shift of the latitude/longitude graticule (lines showing parallels of latitude and meridians of longitude for the earth) is in the range of 10-100 ground meters. Changes to UTM values are generally larger, around 200 meters, and changes for other coordinate systems are different. For more detail...
Image shows a scientific instrument on the slopes of Mount St Helens
The State Plane Coordinate System (SPCS), which is only used in the United States, is a plane coordinate system (north-south and east-west lines are perpendicular) in which each individual state has between one to six zones, depending on the state's size and shape. This coordinate system’s high level of accuracy is achieved through the use of...
Image: Bryce Canyon Benchmark
Most survey marks were set by the U.S. Coast & Geodetic Survey (now called the National Geodetic Survey) and information for those marks is available online. For further assistance, contact the National Geodetic Survey at 301-713-3242 or ngs.infocenter@noaa.gov.  For information about marks set by the USGS, contact the National Geospatial...
Mercator the Man
The UTM (Universal Transverse Mercator) coordinate system divides the world into sixty north-south zones, each 6 degrees of longitude wide. UTM zones are numbered consecutively beginning with Zone 1, which includes the westernmost point of Alaska, and progress eastward to Zone 16, which includes Maine. If UTM ticks are shown on a USGS topographic...
Mercator the Man
The method used to portray a part of the spherical Earth on a flat surface, whether a paper map or a computer screen, is called a map projection. No flat map can rival a globe in truly representing the surface of the entire Earth, so every flat map misrepresents the surface of the Earth in some way. A flat map can show one or more--but never all--...
Image: USGS Aerial Photography and Imagery Library
The question refers to scanned images of traditional aerial photography film products, and these scans are not georectified. If a customer needs them georectified, they will have to do the registration themselves or have that process performed by a provider of value added services.  The USGS does serve other kinds of georectified aerial imagery....
Aldo Leopold Wilderness Research Institute
Currently, some national forests have elected not to participate in the USGS map distribution program. The USGS hopes to carry all the US Forest Service visitor maps in the future. Purchase paper maps for individual national forests using the online USGS Store. Enter the name of the forest in the Keyword Search window or click on Maps/U.S. Forest...
Screenshot of map corner showing two grid lines and their UTM coordinates
The Universal Transverse Mercator (UTM) grid is not used on the Forest Visitor Map series because of the maps’ small scale and intended use. The more detailed Wilderness and Special Area maps published by the Forest Service (some of which are available through the USGS Store) might have UTM grid ticks. UTM grids are included on all US Topo maps (7...
A hiker on the Lower White River Wilderness trail. BLM photo.
Forest Service Visitor Maps are best used to view an entire National Forest. They are great for driving through or planning a trip to the forest  and for showing recreational sites, campgrounds, public information sites, and other attractions in the forest. Wilderness maps and Special Area maps are used to illustrate specific recreation...
Florida National Scenic Trails Maps
Forest Service Visitor Maps are at a smaller scale (i.e. they show a larger area but less detail) than 7.5-minute (1:24,000-scale) USGS topographic maps and typically do not show elevation contours.  Forest Service Visitor Maps include recreational information about camping, fishing, biking, and other outdoor activities.They might also show points...
US map of added trails and recreational points of interest
Trails and symbols US Forest Service maps are clearly shown. A comprehensive legend appears on each map. Since each map is unique, placement of the legend and symbolization might vary from map to map.
U.S. Forest Service (USFS) logo
Yes. On average, the US Forest Service updates its maps every 2 to 7 years.