Getting Help

TopoView lets users access the many and varied older U.S. Geological Survey topographic maps and is especially useful for historical purposes because the names and extents of many natural and cultural features have changed over time. In this detailed guide, we’ll take a tour of the various components of topoView and show you what each can do. Be sure to check out our quick start video to see topoView in action. The video shows live examples of many of the items described in the guide below. Have a question? Contact us. We're here to help.


Topographic maps originally were produced to support a geological survey of the western United States (Powell, 1888). But they quickly became popular with many other disciplines and with the general public because of their usefulness for viewing and studying the Nation’s vast landscape (U.S. Geological Survey, 2010a, 2010b). Technological capability in the early days constrained the broad distribution of maps, and the map libraries served as lending libraries, not as archives. Over time, some maps have been lost from USGS libraries, and therefore no single complete set of USGS historical maps is known to exist. From the beginnings of USGS topographic mapping (ca. 1884) through to the cessation of conventionally-printed (paper) maps, it was not feasible to maintain a comprehensive catalog of all published maps. It is now a significant challenge to find the maps missing from USGS libraries. The USGS is working closely with Library of Congress to discover in its Archives any maps missing from the USGS collection. Further, the USGS is working with local libraries, university geological collections and libraries, and state geological surveys to identify missing maps. All paper topographic maps are scanned and added to the Historical Topographic Map Collection (HTMC). If you are aware of any missing maps, please contact the USGS directly.

Advances in Geographic Information System (GIS) technology motivated the USGS to produce a scanned, georeferenced map series in the mid-1990’s that could be easily integrated into a GIS. These Digital Raster Graphics (DRGs) initially were produced from 1995 to 1998 in partnership with Land Information Technology Company, Ltd. About 1,000 new DRGs were added during the next several years. The objective of that project was to scan and georeference the most recent published version of the USGS standard quadrangle maps for the 7.5-minute, 30x60-minute, and 1x2-degree series (U.S. Geological Survey, 2001a, 2001b). The HTMC uses a higher resolution and more advanced color model than the DRGs, and provides a variety of delivery formats. A more extensive set of metadata is captured and cataloged, and the project provides a permanent digital archive of historical maps that will include all printings and all series of topographic maps produced by the USGS (modified from Allord, 2014).

How to read these maps

The distinctive characteristic of a topographic map is that the shape of the Earth’s surface is shown by contour lines. 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. Contours make it possible to visualize the height of mountains, depths of the ocean bottom, and steepness of slopes. A topographic map may also include many different line and point symbols, for features such as streets, buildings, streams, mines and caves, natural and political boundaries, and vegetation. There is no single document that describes all symbols used on all USGS topographic maps, but to help you read these maps, the USGS provides a variety of symbol guides. Two of particular value include the historical topographic map collection symbols guide (pre-2006), and the US Topo map symbols guide (2009 and more recent). Together, these documents form a fairly complete description of topographic symbols from about 1900 to the present, though it is possible that some unusual symbols are not described in any published document.

Getting around

In most web mapping interfaces, there are a variety of ways to zoom/pan around the map. In topoView, panning is enabled by default. Simply click anywhere on the map, hold down the left mouse button and drag the mouse. For zooming into an area, we offer the magnifier tool, but instead you may find it easier to:

To zoom out click or the icon, which returns you to the initial map view of the conterminous United States. Users can also use the mouse scroll wheel for quickly zooming out of an area. For tablet users, a simple multi-touch pinch gesture lets you zoom in and out of the map area.

There are two related tools that let you toggle between current and previous views, and may be useful if you’ve been navigating around the map. Clicking will return you to the map view just prior to the one you’re currently looking at. If you’ve used   to “step back”, then   will let you “step forward.”

Zoom to location

To find maps for a location, such as your house, or town, or larger area, use the location search bar. There, you can enter very specific information, such as your full street address (e.g., 12201 Sunrise Valley Drive, Reston, VA 20192) or latitude/longitude coordinate pair, or more general information (e.g., zip code, town name, or park name). Note that when using a latitude/longitude pair, longitude is preceded by a minus sign if it is west of the prime meridian (locations in the U.S. for example). TopoView accepts lat/long pairs in both decimal degrees, separated by a comma (38.5, -98.30), or degrees minutes seconds, separated by a comma with spaces between degrees, minutes, and seconds (42 30 00, -98 15 30).

Zoom location

If you provide a unique and specific location, like an address or a zip code, topoView will zoom to the location and generate a list of maps at that point. If you enter something more general (e.g., 'Boston'), you'll see a dropdown list to select from (e.g., Boston, MA; Boston, NY; Boston, TX) – select one, and you'll be zoomed to that feature. If you enter something that's very general (e.g., 'Georgia', or 'Shenandoah Mountains'), topoView will zoom you to the center point of that geographic feature.

Map Records Table

When you click on any of the colored map boxes, a map records table is populated along the right side of the interface and a marker appears on the point that was clicked. By default the active record is expanded and contains information like quadrangle name, map year, map edition, map scale, and a list of downloadable files associated with the record. To make any of the other map records active, simply click that record to expand it. When the map information window is populated, the number of map records and the current filter(s) being applied (specific scale, date range, etc.) are shown above the table of records. The location of the placed marker is also shown along with the elevation (in feet) at that point.

27 maps. Filtered by all scales from 1880 to 2010 near
2065 University Ave, San Jose, CA 95128 | Elev: 114 ft

Map Information

The accuracy of this location is dependent on the zoom level of the map. Markers placed at high zoom levels will return details like street address, whereas those placed at less detailed zoom levels return more generalized location information. If a place name cannot be determined, the latitude/longitude coordinate is displayed.

Name Date Scale State

You can sort records by map name, date, scale, or state name by clicking any of the sort buttons above the map records table. Note that the sort method you choose persists as you populate additional map record tables. This is especially useful if, for example, you always want the oldest map in the collection to take priority in your record table.

Map Information

The information for a particular map can be accessed by simply clicking on the map record. When clicked, the map information window will expand revealing the basic metadata information, the map download options, a list of actions for that particular record (detailed later in this guide), and a preview image of the map (click the preview image to view in high-resolution). The basic metadata at the top of the map information window includes:

Map Name – The printed name of a specific map. Topographic maps published by the U.S. Geological Survey generally are named for the most centrally located and/or well-known or largest community named on the map. If the map contains no communities or they are very rural, small, and scattered, it can be named for the most, prominent and centrally located well-known physical or natural feature. Naming maps for linear features such as streams is generally avoided because such features usually pass through maps or meander on and off the maps. Occasionally, a map area is so devoid of named topography that a directional might be used, as in adding NW or SE to the name of an adjacent map, or even using the map name from a smaller scale series and applying the directional term.

Primary State – The geographic jurisdiction (U.S. State) in which the majority of the mapped area exists on the ground. In border areas showing more than one state (or country), this is the first state (area) listed directly along with the Map Name.

Map Inforamtion

Map Scale – The ratio of a distance on the ground to that distance represented on the printed map. The 1:24,000, (7.5 x 7.5-min) maps are the best known USGS topographic maps. There are about 55,000 map cells of this series in the 48 conterminous states, and about 127,000 individual maps. The difference between 55,000 cells and the 127,000 printed maps in the HTMC is due to reprints, revisions, and variant editions. Although the date range for 7.5-minute maps is more than a century, the overwhelming majority were published between 1947 and 1992. The 1:25,000 scale 7.5 x 7.5-min and 7.5 x 15-min maps are metric variants of the 1:24,000 7.5 x 7.5-min series. Metric maps were produced in selected states during the 7.5-minute program of the late 20th century. The other "primary map series" in the second half of the 20th century were 1:100,000 (30 x 60-min) and 1:250,000 (1 x 2-deg) maps. Alaska was mapped in the 1950's and 60's at 1:63,360 (1 inch = 1 mile). Puerto Rico and U.S. Virgin Islands were mapped at 1:20,000, (7.5 x 7.5-min).

Date on Map – The year in which the map was created. If there are multiple editions with the same "Date on Map," it is suggested you look at the other date(s) available via the "Info" button. These can include things like imprint year, photo inspection year, survey year, etc. (see Map Metadata section for a complete list).

Imprint Year – The year in which the map was printed. In some cases it may appear that there are multiple copies of a map. For a particular cell and scale, most maps have only one original base compilation, but most have later revisions and reprints. Revision methods and extent vary, but most were relatively minor compared to the effort of the original compilation.


A base map, commonly shown as a backdrop to give locational information such as cultural or physical features, is essential to help us locate ourselves on the ground. TopoView offers a variety of base maps which can be toggled in the upper left corner of the map window. Our default base map layer is powered by Mapbox using open data from OpenStreetMap.

OSM editing

If you find an error in the base map (e.g., a street is misnamed), you can submit a correction by clicking the improve link in the bottom left corner of the interface. Once clicked you'll be zoomed to the same area in the OpenStreetMap interface where you can directly edit and/or report your correction.

Downloading Maps

TopoView offers the topographic maps in a variety of downloadable file formats, in order to meet a range of user needs. The GeoTIFF, KMZ, and GeoPDF formats are georeferenced file formats. Georeferencing means that the internal coordinate system of a map can be related to a ground system of geographic coordinates. The relevant coordinate transforms are typically stored within the image file and can be accessed using software that can read this information. Simply click any of the download links for the selected record in the map information window to download the map. The following formats are available for download:

GeoTIFF – The GeoTIFF files are a compressed, TIFF image format, with embedded georeferencing information so that the map can be used directly in a GIS. GeoTIFFs downloadable through topoView are highly compressed 300 dpi TIFF images with georeferencing information embedded in the header. JPEG-in-TIFF compression was used to compress both the tiled TIFF file, and the reduced resolution internal overlays. The GeoTIFFs are generated at true scale, allowing users to plot the map at the intended map scale in cases where a hard copy is needed.

KMZ – Used for displaying maps in Google Earth, the KMZ format is a compressed form of the KML format. Provided you have Google Earth installed on your computer, simply double-click on the KMZ, or drag it into the Google Earth interface. The KMZ file includes information about the particular map that you downloaded in both the places pane, and in the overlay map popup.

JPEG – (Browse JPEG) The high-resolution JPEG format is useful for getting a quick view of the map in order to find place names or simply explore the map area without the need for downloading a larger file. The downloadable JPEG is identical to the image you'll see in your browser when you click on the thumbnail image. But to ensure that the JPEG downloads to your computer, we enclose it in a zip file. Alternatively, simply click on the map thumbnail, and download the JPEG from your browser window.

GeoPDF – A Portable Document Format (PDF) with a geospatial extension, the GeoPDF© is a branded instance of geospatial PDF. GeoPDF's can be viewed and printed with Adobe Reader or comparable PDF viewing software. The geospatial extensions provide limited GIS functionality, such as displaying ground coordinates and measuring distances and areas.

Previewing a Map

TopoView lets users preview any of the historical maps within the interface and provides tools to compare them to a modern base map. Overlaying historical maps on a modern base allows users to explore things like coastline change, urbanization, geographic name changes, and how people have altered the landscape over time.

Map Information

To preview the map record in the interface, simply click the icon on the active map record. Once the overlay is loaded, use the map transparency slider at the bottom of the active record tab to compare the map to the modern base. To remove the map overlay, click the icon above the slider.

Map Metadata

Metadata is the background information which describes the content, quality, condition, and other appropriate characteristics of the data. Paper maps contain metadata, primarily as part of the map legend. In this form, metadata is readily apparent and easily transferred between map producers and map users. When map data are in a digital form, metadata is equally as important, but its development and maintenance often require a more conscious effort on the part of data producers and the chain of subsequent users who may modify the data to suit their particular needs. Clicking the icon reveals selected metadata information for the active map record. Metadata information that is available for the selected record will be tagged with a, metadata fields that do not exist for the selected record will be tagged with a . Users are encouraged to download the metadata file (.xml) that accompanies the GeoTIFF for additional information about the map record. The following fields and corresponding definitions are collected from the map collar:

Advance – A flag that identifies the map as an advance copy or sheet.

Aerial Photo Year – The year of the aerial photography used in the creation of the map.

Datum* – A mathematical model that approximates the size and shape of the earth. This field is used to identify the specific datum used to create the map.

Edit Year – The most recent year that the map was substantially edited or revised.

Field Check Year – The year the map content was last verified in the field.

GNIS Cell ID – The Geographic Names Information System (GNIS) permanent, unique identifier for geographic quadrangles.

GNIS Cell – The GNIS quadrangle name for the selected record.

Interim – A flag that identifies the map as an interim edition.

Orthophoto – A flag that identifies the map as one that includes an orthophoto.

Photo Inspection Year – The year when a photo inspection was last done on the map.

Photo Revision Year – The year when new photos were used to revise a map.

Planimetric – A flag that identifies the map as one that has no elevation contours.

Preliminary – A flag that identifies the map as a preliminary sheet or edition.

Publisher – The information header that identifies the Federal agency that produced or cooperated in the production of the map. Publishers/cooperators can include the U.S. Geological Survey, the U.S. Army Corps of Engineers, the U.S. Army Map Service, the U.S. War Department, the U.S. Forest Service, the Bureau of Reclamation, the Bureau of Land Management, the National Park Service, the Bureau of Indian Affairs, the U.S. Environmental Protection Agency, the Tennessee Valley Authority, the U.S. Department of Commerce, or other military agencies.

Projection – A mathematical model used to represent the spherical shape of the earth’s surface on a flat surface (paper map). This field identifies the specific projection used to create the map.

Provisional – A flag that identifies the map as a provisional copy or sheet.

Shaded Relief – A flag that identifies the map as one that includes a 3-dimensional shadow effect enhancing visualization of terrain relief.

Special Map – A flag that identifies the map as an oddly sized or off-grid map that was created for a special purpose.

Special Printing – A flag that identifies the map as one that has no Woodland Tint and no elevation contours.

Survey Year – The year when a field survey was completed.

Woodland Tint – A flag that indicates whether or not the map included Woodland Tint or National Forest (assumes woodland present inside National Forest).

*NAD27 is used in the scanned historical topographic quadrangle collection because the difference between NAD27 and the older datums is negligible as compared to error inherent in the older maps. The following excerpt was originally quoted from a National Academy of Sciences (1971, p. 7) report titled North American Datum:

"The first official geodetic datum in the United States was the New England Datum, adopted in 1879. It was based on surveys in the eastern and northeastern states and referenced to the Clarke Spheroid of 1866, with triangulation station Principio, in Maryland, as the origin. The first transcontinental arc of triangulation was completed in 1899, connecting independent surveys along the Pacific Coast. In the intervening years, other surveys were extended to the Gulf of Mexico. The New England Datum was thus extended to the south and west without major readjustment of the surveys in the east. In 1901, this expanded network was officially designated the United States Standard Datum, and triangulation station Meades Ranch, in Kansas, was the origin. In 1913, after the geodetic organizations of Canada and Mexico formally agreed to base their triangulation networks on the United States network, the datum was renamed the North American Datum."

"By the mid-1920’s, the problems of adjusting new surveys to fit into the existing network were acute. Therefore, during the 5-year period 1927−1932 all available primary data were adjusted into a system now known as the North American 1927 Datum. The coordinates of station Meades Ranch were not changed but the revised coordinates of the network comprised the North American 1927 Datum."

Historical maps published prior to the 1970's typically have a vertical datum referenced to local mean sea level. After that, the National Geodetic Vertical Datum of 1929 (NGVD29) was used for most maps. Elevation values retuned by the interface on mouse click/tap or using the spot elevation tool are referenced to the North American Vertical Datum of 1988 (NAVD88), although the NGVD29 and local reference datums are used in some areas outside of the conterminous United States (CONUS). For Hawaii, Puerto Rico, U.S. Virgin Islands, and Pacific Island territories, the vertical datum is typically referenced to local mean sea level.

Map Scales

When you enter the topoView site, you'll see colored boxes overlying the conterminous U.S. and Alaska. These colors depict common USGS map series scales. By default, all maps at all scales are shown. If you'd like to filter by a certain map scale, click any of the map scale icons to choose which map scale to view. In the example below, we show the distribution of topographic maps of different scales around the Seattle area. As we select a map scale, note that the records table is automatically filtered to show only maps in the selected scale bin.

Select Scales

It's common to see map scales listed as representative fractions (e.g., 1:100,000). For example a 1:24,000 map means that 1 unit of measurement on a map – 1 inch, or 1 centimeter, or 1 foot – represents 24,000 of that same unit on the ground. The smaller the map scale number, the more detailed the map is, but the less area it covers. Learn more about map scales.

The scale numbers in the map scales selector box represent common USGS map series scales. In order to provide a useful but compact Map Scale selector, we combined maps of similar scale into bins shown in the map scale icons. The All bin includes all maps, at all scales (default). The 250K bin includes only 1:250,000 scale maps. The 100K bin includes 1:96,000, 1:100,000, and 1:125,000 scale maps. The 63K bin includes 1:62,500 and 1:63,360 scale maps. The 48K bin includes 1:48,000 and 1:50,000 scale maps. The 24K bin includes 1:10,000, 1:12,000, 1:20,000, 1:21,120, 1:24,000, 1:25,000, 1:30,000, and 1:31,680 scale maps. Note that when a map scale is selected (with the exception of 'All'), map labels will appear as you zoom in.


Topographic mapping of the United States began in the late 1800's. The first maps were of large areas, at scales of 1:125,000 and 1:250,000 (see Map Scales section). As mapping of the country progressed, more detailed maps were made, and by the 1930's, mapping at 1:24,000 was being done systematically (the 1:24,000 scale provides highly detailed map information to the public, and has become the USGS's principal topographic map product).


The timeline slider, along the top of the records table, will let you view and download maps of any time interval you choose. In addition, it's a powerful, easy-to-use tool for learning about the progression of topographic mapping across the country over time.

If you've selected a time interval (for example, to show the maps published between 1889 and 1927), then all maps that are not within that interval will be excluded from searches and from the map records table. If you want to be sure to find a map of your area, reset the timeline to the full extent*.

*Note you can easily reset all filters to default by simply clicking the icon at the top of the map records table. It will become active (red) when any combination of map scale, timeline, or keyword search filters are in place.

Searching maps

If you know the name of the map you're looking for, you can enter it in the search bar above the record table by clicking the "Map Name" tab. We've preloaded all the quadrangle names in the HTMC so as you type the search bar will auto-populate quadrangle names in a dropdown menu. As you add more characters to the search bar, the autocomplete function will further refine that list. If you see the quad you're searching for in the dropdown list, simply click on it or tab down to the record to run the search. If you'd rather search without using autocomplete, just enter your search term and click the search icon or press the enter key. Search terms can be full names, or just partial names.

In the example below we entered "shel" and selected one of the autocomplete choices ("Musselshell Quad", 7 maps records). Next, we ran the same search without choosing an autocomplete return and obtained 232 map records with the term "shel" somewhere in the map name.

Search maps

Once the search term is entered, the record table will be populated with the records that meet your search criteria and you'll be zoomed to the extent that includes all the maps in your search. You can further refine your search by using the timeline and/or scale selector either before, or during, an active search. Be aware that your search will be limited to the current timeline and map scale that you've selected. To increase the odds of finding the map, reset the timeline and set the map scale selector to "All".

Your Location

TopoView allows you to see maps at your current location by clicking on the icon. If you have geolocation services enabled on your device/browser, you will be zoomed to your current position. Note that the accuracy of the geolocation tool depends on a variety of factors including user hardware (GPS enabled) and network connection. Location accuracy is depicted in the circle around the estimated location. A large radius usually indicates that topoView is geolocating based on the device's IP address.

If you pan or zoom to another area, you can re-center your location by clicking the icon again. Note that when your location is no longer centered, the geolocation icon is highlighted yellow. To turn off geolocation simply click the geolocation icon while your location is centered.

Coordinate Systems

You can see the coordinates of any location, simply by positioning the mouse over that location. You can easily switch between common coordinate reference systems using the coordinate system tool. Click any of the coordinate buttons at the bottom of the interface (shown below) to toggle between reference systems.. By default, the coordinate tool presents geographic coordinates in degrees-minutes-seconds of latitude and longitude. (Latitude is the angle from the center of the Earth to some east-west line on the Earth's surface. Longitude is the angle from the center of the Earth to a north-south line on the Earth's surface.) The numerical values for latitude and longitude can be represented in a number of different formats. TopoView supports both Decimal Degrees (DD) and Degrees Minutes Seconds (DMS) formats. The first method divides each degree into 60 minutes (1° = 60'), then each minute into 60 seconds (1' = 60"). The second method simply states the fraction as a decimal of a degree.

Lat: 40° 15' 30'' N    Long: 109° 35' 30'' W

DMS DD MGR UTM Click the buttons above to switch between coordinate systems

The Universal Transverse Mercator (UTM) coordinate system is a grid-based method for specifying coordinates developed by the U.S. Army Map Service for military purposes. In this grid, the Earth is divided into 60 north-south zones, each covering a strip 6° wide in longitude (with a few exceptions). Zones are numbered consecutively beginning with Zone 1 and progressing eastward to Zone 60.The conterminous 48 States are covered by 10 zones, from Zone 10 on the west coast through Zone 19 in New England. In each zone, coordinates are measured north and east in meters. The northing values are measured continuously from zero at the Equator, in a northerly direction. To avoid negative numbers for locations south of the Equator, cartographers assigned the Equator an arbitrary false northing value of 10,000,000 meters. A central meridian through the middle of each 6° zone is assigned an easting value of 500,000 meters. Grid values to the west of this central meridian are less than 500,000 and more than 500,000 to the east. UTM coordinates are presented in the format "longitude zone, latitude zone easting northing", where easting is the projected distance from a longitude zone's central meridian and northing is the projected distance from the equator.

The Military Grid Reference System (MGRS) is an extension of the UTM system but further divides each UTM zone to 100 km by 100 km squares. The system uses a set of two alphabetic characters for each of the 100 km grid squares. The first letter is the east-west position within the longitude zone and the second letter is the north-south position. Starting at the 180 degree meridian the characters A to Z (I and O omitted) are used for 18 degrees before starting over again. From the equator north, the characters A to V (I and O omitted) are used for 100 km squares, repeating every 2,000 km. Northing designators normally begin with "A" at the equator for odd numbered UTM easting zones. For even numbered easting zones the northing designators are offset by five characters, starting at the equator with "F". TopoView uses a MGRS 10 digit coordinate (1-meter square). Learn more about MGRS and other coordinate systems.

To use the Spot Elevation Tool, click the icon. Crosshairs will be added to the center of the map interface and the elevation/coordinates of the map point centered in the crosshairs will be displayed above the tool. This is useful spot checking features on the map or for copy/pasting precise feature coordinates from topoView.

Sending Us Feedback

Help us make topoView more useful for you by telling us how we can better deliver our products to you or report any problems you have experienced with the site. Have you found any broken links or out-of-date information? Encounter an issue with data downloaded from the site? We'd like to hear about it and read all feedback carefully. The best way to send us comments is by using our comments form. You can access the comments form by clicking the icon. Here you can send us your questions, comments, and suggestions either anonymously or with your contact information if you'd like direct repsonse.

Sometimes you may find a particular map that has an error or isn't showing up in the right place when you preview it in the interface. We've made it easy for you to send us a notification about that particular record in question. Simply click the icon under the thumbnail graphic in the active map record pane. Once clicked, the comments form will open populated with the unique map ID in the comments form.

General Settings

You can control some of the basic configuration settings for topoView by clicking the icon. The general settings pane lets you toggle the display of the map bounding box overlays, or modify their opacity if they are being shown. The opacity slider is particularly helpful for seeing the underlying roads, towns, and topographic information on the selected base map. The settings pane also allows users to switch between light and dark themes within the topoView interface. The dark base provides a neutral background with minimal colors allowing the thematic overlays to come to the foreground.

Sharing & Pinning

Click on the icon to open the sharing window. The sharing window lets you send your current topoView window settings to your favorite social networking sites like Twitter and Facebook. You can also copy the URL string for pasting in a text editor, or for sharing via email or web browser.

Search maps

Click on the icon in the map information window to pin your map. Pin descriptions are pre-built with information about the map being pinned. Descriptions can be edited if a customized description is desired. Note that the social networking capabilities in topoView require you to have an account with the particular social networking service you're interacting with.


Allord, G.J., Fishburn, K.A., and Walter, J.L. 2014, Standard for the U.S. Geological Survey Historical Topographic Map Collection (ver. 2, July 2014): U.S. Geological Survey Techniques and Methods, book 3, chap. B11, 11 p.

National Academy of Sciences, 1971, North American datum: National Ocean Survey contract rept. E-53-69(N), 80 p., 7 figs.

Powell, J.W., 1888, Methods of geologic cartography in use by the United States Geological Survey, in Congres Geologique International, Compte Rendu de la 3me Session, Berlin, 1995: A.W. Schade’s Buchdruckerei, Berlin, p. 221-240.

Snyder, J.P., 1987, Map projections – A working manual: U.S. Geological Survey Professional Paper 1395, 383 p. and 1 plate.

U.S. Geological Survey, 2010, 125 years of topographic mapping. A variety of resources related to the history of the National Program for Topographic Mapping (1884–2009).

U.S. Geological Survey, 2001a, Part 1 Specifications―Standards for digital raster graphics, National Mapping Program Technical Instructions: 13 p.

U.S. Geological Survey, 2001b, Part 2 Specifications―Standards for digital raster graphics, National Mapping Program Technical Instructions: 30 p.


Useful information about the FGDC metadata standard. The FGDC standard outlines the requirements related to the inventory, documentation, and service of metadata for digital spatial data in the federal government.

The USGS home page for the U.S. Board on Geographic Names. The U.S. Board on Geographic Names maintains uniform geographic name usage throughout the Federal Government.

The USGS home page for The National Map. The National Map is a collaborative effort among the USGS and other Federal, State, and local partners to improve and deliver topographic information for the Nation

The USGS home page for the scanned Historical Topographic Map Collection (HTMC). The HTMC is a digital repository of USGS 1:250,000 scale and larger maps printed between 1884, the inception of the topographic mapping program, and 2006.

The USGS home page for the US Topo maps. US Topo maps are quadrangle topographic maps published in 2009 and later. These maps are modeled on the familiar 7.5-minute quadrangle maps of the period 1947-1992, but are mass-produced from national GIS databases on a repeating cycle.

The home page for the USGS National Geospatial Program. The National Geospatial Program provides leadership for USGS geospatial coordination, production and service activities.

The home page for the National Geologic Map Database project (NGMDB). The NGMDB provides standardized, spatial geoscience information for the Nation.

The home page for the USGS Store. The USGS store is a one-stop shop for users to purchase products created and distributed by U.S. Geological Survey.

The home page for the International Organization for Standardization (ISO). The ISO is an independent, non-governmental international organization that brings together experts from over 163 national standards bodies to develop voluntary, consensus-based, market relevant International Standards.

The home page for the Open Geospatial Consortium (OGC). The OGC is an international not for profit organization committed to making open standards for the global geospatial community

The home page for the Open Source Geospatial Foundation (OSGeo). OSGeo was created to support the collaborative development of open source geospatial software, and promote its widespread use.