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Geographic Information Systems (GIS) & Geospatial Resources

Geospatial Data

Map poster student project on Arlington Fire Stations

Kelly Burdette and Arlington County GIS Center. An Analysis of Fire Stations in Arlington, Virginia. 2016. Geography & Map Division.

Geographic Information Systems (GIS) software allows users to create, edit, and transform geospatial data, which seeks to measure and represent the world's geographic features. Anything which exists physically on the globe -- from people to houses to agricultural fields to cloud cover -- can be measured or counted and associated with a geographic location or set of coordinates. Geospatial data pairs tabular descriptive data (often referred to as attribute data) with a geometric map feature (point, polygon, line, or cell). When mapping an urban area, one spatial data layer may contain the street pattern of the city, another the administrative districts of the city, and a third might show the demographic information of the population across neighborhoods. Within GIS, each type of data can be tailored to meet specific criteria, and each layer combined to form a single map. Data layers can also be operated on and transformed to conduct spatial analysis. Cartographers and GIS Specialists in the Geography & Map Division utilize geospatial data directly in cartographic work for House and Senate offices.

Geospatial Data Preservation

In order to maintain its unparalleled collection of cartographic materials, the Library of Congress develops and implements strategies led by the Geography & Map Division for the acquisition of digital geospatial data. A major portion of the sum of present-day human knowledge in the subjects of geography and cartography is expressed in digital geospatial data and related digital technologies. The Library collects geospatial data from a wide range of sources, in domestic and global geographic coverage, and in a variety of data file formats and themes. Additionally, the Library endeavors to capture the world's geographic, geospatial, and cartographic heritage. To learn more about the Geography and Map Division's geospatial collections, view our Collections Policy Statement for Digital Geospatial Materials.

For more information on the types of geospatial file formats currently collected by the Library of Congress, see the GIS, Geospatial and Non-GIS Cartographic Recommended Format Statement. The Library of Congress Sustainability of Digital Formats and Geospatial section provides detailed information on geospatial file formats at large.

The Geography & Map Division curates the Geospatial Software and File Formats Documentation Web Archive, which is expected to debut on the Library's web site in mid-2024.

Accessing Geospatial Data

There are many places to access catalogs of available geospatial data. The US government is a major provider of publicly available geospatial data and a significant source of value-added geospatial data from third parties. For example, the USGS holds decades worth of publicly available satellite data and provides numerous derivative products from land use/land cover to spectral indices to base maps. The Census Bureau produces TIGER/Line geospatial products which provide a base for many transportation and navigation derivative geospatial products. These federal geospatial datasets and many others can be found through the GeoPlatform Portal, which was developed by the Federal Geographic Data Committee (FGDC). The GeoPlatform Portal was recognized as an access point for federal geospatial data by the Geospatial Data Act of 2018.

The Geography & Map Division currently provides select geospatial datasets available online. To inquire about viewing geospatial datasets under copyright in the Geography and Map Reading Room, please contact the Geography and Map Division through Ask a Librarian.

Select Geospatial Datasets

Posts about GIS/Geospatial Data from Worlds Revealed Blog

Worlds Revealed is the blog of the Library of Congress Geography & Map Division. Since 2015 the blog has explored the past, present, and future of maps and mapping through the lens of the division's collections.

These selected posts relate to GIS or Geospatial Materials: