Become familiar with terminology related to cartographic and geospatial information
Learn about the primary agencies that produce maps and geospatial data
Develop and understanding of the information contained in land records
Governments are responsible for much of the mapping and geospatial data available both at the national and local levels. This chapter will introduce the main mapping products available from federal, state, and foreign governments.
It’s important to understand some basic map terminology in order to assist patrons with finding the best map for their needs. Many patrons have never learned how to read a map and may need instruction on how to interpret the information presented on a map or aerial photograph.
- Scale is a ratio that refers to the proportion of measurements on a map to the features they represent. For example, a scale of 1:24,000 means that one inch on the map represents 24,000 inches on the ground, or 2,000 feet. Scale can be indicated using a statement, a representative fraction, or by a bar. The larger the number, the smaller the scale. In other words, a ratio like 1:1,000,000 would be found on a small-scale map that covers a very large area, whereas a large-scale map with a scale of 1:12,000 would provide more detail of a much smaller area.
- Projection refers to a method of mathematically representing the round earth on a flat surface. Some projections distort distance, while others distort the shapes of land masses. The U.S. Geological Survey has produced a poster that shows examples of the most commonly used projections on its maps.
- Coordinate systems are used to express relative location on the earth’s surface. They are displayed as the gridlines that appear on a map. There are two main types of coordinate systems:
- Geographical coordinates, using latitude and longitude.
- Rectangular or plane coordinates based on a Cartesian coordinate system. Coordinate systems commonly used on maps in the U.S. are the Universal Transverse Mercator (UTM) system and the State Plane Coordinate system (SPC).
In the United States, several agencies produce printed and interactive maps for their constituencies. In addition to mapping products, they also provide downloadable geospatial data for use with geographic information systems (GIS) software. This chapter will cover the most important mapping agencies of the U.S. government. The recently developed GeoPlatform.gov is intended to be a single interface to obtain data from the National Geospatial Data Assets and contains over 160,000 datasets. Data.gov is another interface to search for government-produced geospatial information (both federal and local) by subject.
The USGS has been distributing maps to depository libraries since the late 19th century. It has produced dozens of map series such as topographic maps at different scales, geologic maps, maps of mineral and water resources, and many others. Today, the USGS provides access to much of its geospatial data through the National Map, a collaborative site that allows users to create dynamically generated maps by choosing a location and the desired map layers showing characteristics such as elevations, transportation, and land cover. It is also the gateway for downloadable data.
Topographic maps show topography—in other words, the elevations, peaks, valleys, bodies of water, transportation networks, and physical and man-made features of the land. USGS topographic maps are issued in 7.5-minute quadrangles, commonly referred to as topo quads, at a scale of 1:25,000 for most of the U.S. and 1:62,000 for Alaska. These large-scale maps are very popular because they show details and place names for relatively small areas. Many federal depository libraries formerly collected complete sets of current and historical topographic maps for their states and adjoining states, and regional depositories received maps for the entire U.S. and its territories. In 2006, the USGS stopped issuing printed maps and began publishing topographic maps online with print-on-demand service for them. In a number of states, libraries or archives have scanned their collections of historical topographic maps and published them online.
The USGS maintains science centers in each state and territory. They connect users with maps, downloadable data, news about current earth science-related events such as earthquakes and floods, and research publications. Some states also have USGS Volcano Observatories.
USGS offers the following datasets:
- National Hydrography Dataset
- Watershed Boundary Dataset
- Transportation, Structures and Boundaries
- National Land Cover Database
- Digital Elevation Models
Part of the Department of Commerce, NOAA and its subagencies produce data related to weather, climate, oceans, fisheries, and other topics. NOAA collects satellite imagery for climate and storm monitoring. The National Weather Service (NWS) hosts a variety of satellite images showing water vapor and other weather characteristics and prediction tools. NWS also produces temperature and climate maps. The Office of Coast Survey produces nautical charts for U.S. coastal waters. Nautical charts show water depths, aids and hazards to navigation, coastlines, harbors, and coastal landmarks. Because the charts are constantly being updated, libraries that do not manually update them must stamp them “Not for navigation.” But, navigation is only one potential use for nautical charts. Researchers often consult nautical charts for their detailed views of coastal features, islands, and .
The Army Map Service (AMS) established a depository system after World War II to distribute surplus AMS-produced maps as well as captured German and Japanese maps of various parts of the world. AMS became the Defense Mapping Agency (DMA) in 1972 and continued to distribute mostly aeronautical and nautical charts to its depository libraries. DMA eventually ended its own depository system and began to distribute maps through the FDLP. DMA evolved into the National Imagery and Mapping Agency (NIMA), currently known as the NGA, which still produces aeronautical and nautical charts for non-U.S. areas. The main series of aeronautical charts are TPC (Tactical Pilotage Chart), ONC (Operational Navigation Chart), and JOG (Joint Operations Graphic). While intended for use in aircraft navigation, these maps are valued by libraries because they can serve as topographic maps for regions where such maps are unavailable or at too small a scale to be useful.
The USACE produces navigation charts of the navigable inland waters of the United States, such as the Mississippi River. Many can be found in the USACE Digital Library. It also creates maps of harbors, flood control projects, and other USACE projects.
Maps are one of the few types of publications available from the CIA. The agency produces political maps of many countries that show major features and boundaries in small and medium sizes. Current editions may also be downloaded from the CIA website. Historical CIA maps are available from the Perry-Castañeda Library at the University of Texas at Austin.
The Census Bureau produces both static maps and online tools that allow users to dynamically generate maps showing desired characteristics. Static reference maps show boundaries of geographic units like census tracts, congressional districts, or census-designated places. Thematic maps display frequently-requested data such as population, income, and poverty. User-generated maps can display data like business establishments, population density, or income for a selected geographic area. OnTheMap is an online tool that enables users to map economic flows such as where people live and where they work. The data can be used by planners to anticipate housing and transportation needs.
The Census Bureau also produces TIGER/Line files, downloadable geospatial data in the form of shapefiles that can be used in GIS applications. TIGER stands for Topologically-Integrated Geographic Encoding and Referencing. The files include statistical and political boundaries, transportation networks, and bodies of water. TIGER data is updated annually, and it’s important to note that users should use the TIGER files that are of the same vintage as the demographic data to be used to ensure that geographic boundaries match. TIGER files do not contain the actual census data, but they can be joined to data tables to enable the creation of maps. The Census Bureau’s geospatial data can also be found in Data.gov.
The Forest Service publishes maps of all of the national forests and recreation areas within them. You can even find recreation maps for areas partially outside national forest boundaries, such as the Columbia River Gorge. Note that many maps are for sale but are not available as downloads.
The Natural Resources Conservation Service (NRCS, formerly the Soil Conservation Service) produces soil surveys with detailed maps of the different soil types for every county in the U.S. and its territories. The Soil Survey Geographic Database allows access to digital soils data, which can be used to determine the suitability of a piece of land for crops, buildings, basements, septic systems, and other potential uses. The NRCS and the Farm Service Agency (FSA) collect aerial photography related to agriculture, water resources, roads, and other features. Many libraries have digitized historical aerial photographs of their states. For example, Aerial Photographs of Colorado is hosted by the University of Colorado at Boulder.
The Food Environment Atlas is a product of the Economic Research Service. It allows users to display maps related to food insecurity, food and health, food assistance programs like Women, Infants, and Children (WIC) and Supplemental Nutrition Assistance Program (SNAP, aka food stamps), participation in school breakfast and lunch programs, food prices, and other characteristics. Unfortunately, the atlas does not include U.S. territories. A related product, the Food Access Research Atlas, allows users to create their own maps showing income, and transportation factors that impact access to food. The Atlas of Rural and Small-Town America allows users to view data on rural population change, rural unemployment, income, and other characteristics of rural America.
The FAA’s Aeronautical Information Service produces aeronautical charts and other aids to flight navigation in the U.S. in both printed and digital form.
One of the most important products available from FEMA is flood insurance rate maps (FIRM), typically used to determine the flood risk of a property. The maps were formerly sent to depository libraries and are now available online, as is the National Flood Hazard Layer dataset.
BLM produces downloadable maps of land it manages in the western U.S. and recreational areas that fall under its jurisdiction. BLM also hosts the General Land Office database that contains the full text of land conveyance records for .
USBR manages water resources in the western U.S. The Bureau is most widely known for its dam construction and irrigation and hydropower projects. It produces maps of recreation areas and other publications related to USBR dams and reservoirs.
An important source of maps is environmental review documents such as environmental assessments (EAs) and environmental impact statements (EISs). They often contain maps of archaeological sites, topographic maps, aerial photographs, and other types of maps. EISs are discussed in more detail in Chapter 9.
Remote sensing describes the acquisition of geospatial information using cameras or other equipment mounted on aircraft, satellites, boats, balloons, or other platforms. The data collected can be used for an infinite variety of purposes, such as mapping topography or , analyzing land use and land cover, or following weather phenomena or forest fires. In addition to government-sponsored remote sensing programs, much satellite imagery and aerial photography is acquired by commercial operators and is not discussed here because it exceeds the scope of this text.
Aerial photographs are frequently sought because they provide a point-in-time view of a place. Many aerial photography surveys have been undertaken by USGS, USDA, and NOAA. In addition, NASA has published photographs of earth taken from the Space Shuttle.
USGS manages the National Aerial Photography Program (NAPP), a collection of aerial photographs used to update topographic maps. The historical collection of aerial photographs from several programs extends back to 1939. USGS Earth Explorer allows users to search for aerial photographs, satellite imagery, and other geospatial data by coordinates or street address.
Satellites carry scanners that acquire imagery to serve specific purposes, such as analysis of land use and land cover, weather, defense intelligence, and other uses. USGS operates the Landsat satellite program with NASA, resulting in “the largest civilian collection of images of the Earth’s land surface in existence, including tens of millions of satellite images.” Satellite imagery from Landsat and other programs is available through USGS’s Earth Resources Observation and Science Center.
The National Environmental Satellite, Data, and Information Service (NESDIS) of NOAA operates a fleet of environmental satellites that provide imagery showing weather and environmental information, including atmospheric and meteorological data, sea level, sea ice, flooding, and many other topics.
Radar (radio detection and ranging), a technology based on the detection of microwave radiation, is familiar to most of us. Radar is commonly used by the National Weather Service to capture weather phenomena and data is available from the National Centers for Environmental Information.
Light Detection and Ranging (LIDAR) is a type of remote sensing that uses laser pulses to acquire data from an aircraft, satellite, or boat. It is used for coastal hazard evaluation, bathymetric mapping, coral reef monitoring, and other applications. LIDAR imagery is available from NOAA’s Digital Coast site. Some states also provide LIDAR data through portals like the Washington Lidar Portal.
Patrons frequently seek maps for recreational or travel purposes. Although the information may be available in commercially published maps or atlases, official state-issued maps are more authoritative and as an added bonus, they are usually free. Many state highway divisions and state tourism promotion offices publish highway maps. In addition, some states, cities, and counties publish specialized maps for bicyclists, snowmobilers, off-road enthusiasts, and other audiences. For instance, Maine’s Department of Transportation produces maps of its scenic byways.
Each state has a geological survey that works with the USGS and produces maps and other geology-related publications about the state or region. The range of publications and mapping products varies but usually includes maps, downloadable data, and technical reports. For example, the Florida Geological Survey produces digital maps of springs, aquifers, landforms, and subsidence incidents, while Wyoming’s State Geological Survey offers interactive maps for ground water, oil and gas, mines and minerals, and geologic hazards.
Researchers seek historical maps for a variety of reasons. They may be studying urbanization, shifts in road alignments or streambeds, changes in land use, or details about land ownership. Fortunately, many state archives, historical societies, and university libraries have digitized portions of their historical map collections.
The Library of Congress’s Geography and Map Division has digitized many of its historical government-produced maps, including maps by Army exploring expeditions, USGS, National Park Service, and other agencies.
The National Archives holds land transaction records from the General Land Office, predecessor of the Bureau of Land Management, for the 30 . The records cover sales of land by the U.S. to individuals and do not include subsequent transactions. States not included are the original 13 colonies, plus Hawaiʻi, Kentucky, Maine, Tennessee, Texas, Vermont, and West Virginia. Records for these 20 states are held by the state archives or land agency. You can search the records online via the BLM’s General Land Office Records site.
The David Rumsey Collection has digitized tens of thousands of important historical maps and atlases, including historical California state highway maps and other states’ highway maps dating back over a century.
Each state has a land survey office or other department that coordinates with the National Geodetic Survey. These state survey offices are often a treasure trove of historical maps. If you are lucky, the state will have digitized its plat maps and survey field notes, as the Nebraska State Survey Office has done.
The Map and Geospatial Information Round Table (MAGIRT) of the American Library Association is in the process of creating an online guide to U.S. map resources to update the book Guide to U.S. Map Resources.
A GIS facilitates the combination of geospatial and thematic data to create maps and perform data analysis. GIS data is often available in the form of shapefiles, which can be used in specialized GIS software. All states have a GIS or geological survey office that provides access to geospatial data and mapping products. For example, the Geological Survey of Alabama links to a number of geospatial databases, downloadable topographic maps, geologic maps, and other resources. The University of Maryland Library maintains a guide that lists state GIS offices.
Most national governments have one or more mapping agencies that issue topographic maps of the entire country. A famous example is the Ordnance Survey of Britain. Mapping for countries that lack the capacity to create their own maps has been performed by former colonial governments or other countries, so they may not be kept up to date. This is especially true for nautical charts, many of which have not been revised in decades. In some countries, the availability of large-scale (more detailed) geospatial information is restricted. Furthermore, most maps produced by foreign governments are not freely available electronically due to copyright or other restrictions.
Some libraries collect government- and commercially-produced maps for area studies collections. Many government map series have been distributed through the Library of Congress’s Cooperative Acquisition Program that operates field offices in Asia, the Middle East, Latin America, and Africa. To learn which libraries have extensive collections of foreign maps, consult Guide to U.S. Map Resources. LC has also digitized a number of historical maps including maps of foreign countries.
See Chapter 12 for more information about foreign government publications, including maps.
Several vendors specialize in selling government mapping and geospatial products:
EastView Geospatial sells worldwide topographic and geologic maps, nautical and aeronautical charts, aerial and satellite imagery, GIS data, and the Global Census Archive of census data for Latin American countries, Japan, and South Africa.
LandInfo Worldwide Mapping sells worldwide digital topographic map and nautical chart data and aerial and satellite imagery.
The Perry-Castañeda Library maintains a list of map vendors (not all of them offer government-produced maps).
U.S. Geological Survey. Topographic map symbols. http://go.hawaii.edu/2i3
An essential reference for understanding the symbols used on U.S. topographic maps.
Hawkins, K. (Compiler). (2009). Research in the land entry files of the General Land Office. Washington, D.C.: National Archives and Records Administration. Reference Information Paper 114.
This volume explains the contents of the Land Entry Case Files and how to research tract books at NARA.
Kollen, C., Shawa, W., & Larsgaard, M. L. (2010). Cartographic citations: A style guide. (2nd ed.). Chicago: Map and Geography Round Table, American Library Association.
No other guide addresses citation of cartographic resources in as great a depth as this classic work.
Larsgaard, M. L. (1998). Map librarianship: An introduction. (3rd ed.). Englewood, CO: Libraries Unlimited.
Mary Larsgaard, a longtime map librarian at the University of California at Santa Barbara, was considered the guru of map librarianship. Although dated, this book is essential for understanding types of maps, map acquisition, cataloging, preservation, and other issues.
Parry, R. B., & Perkins, C. R. (2002). World mapping today. (2nd ed.). Munich: K.G. Saur.
This volume is an attempt to describe the mapping products available for all of the world’s countries and where to obtain maps. Even though it was published almost 20 years ago, it is still an essential source for determining the cartographic information available for foreign countries.
Thompson, M. M. (1988). Maps for America: Cartographic products of the U.S. Geological Survey and others. Reston, Va.: U.S. Department of the Interior, Geological Survey.
Maps for America offers a detailed overview of the USGS and other agencies’ geospatial products, Although dated, it gives thorough explanations of each type of geospatial information products and includes numerous illustrations of maps, aerial photographs, and satellite imagery.
U.S. Department of the Army. (1956). Foreign maps. Technical manual 5-248. Washington, D.C.: Department of the Army.
This volume explains the idiosyncrasies of various map series produced by foreign governments. It includes black and white and color images of foreign maps.
U.S. Geological Survey. The Public Land Survey System (PLSS). https://nationalmap.gov/small_scale/a_plss.html
This brief article explains the history of the PLSS and how it varies regionally.
U.S. National Geospatial-Intelligence Agency. GEOnet Names Server. http://geonames.nga.mil/
The GEOnet Names Server (GNS) serves as a kind of authority control for foreign place names. It is “the official repository of standard spellings of all foreign geographic names, sanctioned by the United States Board on Geographic Names (US BGN). The database also contains variant spellings (cross-references), which are useful for finding purposes, as well as non-Roman script spellings of many of these names.”
U.S. Geological Survey. Geographic Names Information System. https://geonames.usgs.gov/
“The Geographic Names Information System (GNIS) is the Federal and national standard for geographic nomenclature. The U.S. Geological Survey developed the GNIS in support of the U.S. Board on Geographic Names as the official repository of domestic geographic names data.”
- Robinson, A. H., Morrison, J. L., Muehrcke, P. C., Kimerling, A. J., & Guptill, S. C. (1995). Scale, reference, and coordinate systems. In Elements of Cartography. (6th ed.). Hoboken: John Wiley & Sons, 91-111. ↵
- Morehead, J. (1999). Geographic information sources. In Introduction to United States Government Information Sources (6th ed.). Englewood, CO: Libraries Unlimited, 407-428. ↵
- U.S. Geological Survey. Earth Resources Observation and Science (EROS) Center. https://www.usgs.gov/centers/eros ↵
- Thiry, C. J. J. (Ed.). (2006). Guide to U.S. map resources. (3rd ed.). Lanham, Maryland: Scarecrow Press. ↵
- Thiry (2006). ↵
Bathymetry refers to submarine topography, or the hills, valleys, chasms, and other features of the ocean floor.
Public Land States are those that were formed from public lands. Western public land states: Alaska, Arizona, California, Colorado, Idaho, Kansas, Montana, Nebraska, Nevada, New Mexico, North Dakota, Oklahoma, Oregon, South Dakota, Utah, Washington, and Wyoming. Eastern public land states: Alabama, Arkansas, Florida, Illinois, Indiana, Iowa, Louisiana, Michigan, Minnesota, Mississippi, Missouri, Ohio, and Wisconsin.
Land patents are the legal documents that transferred land ownership from the U.S. Government to individuals.