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GIS Mapping Data Sources

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GIS is a critical tool for planners; however, access to detailed, up-to-date data layers can be difficult to find.  GIS can be used to understand community landscapes in many different planning functions and in a variety of applications.  In order to create informative maps and conduct useful analysis, planners need access to a range of data sets that provide information on a variety of topics and issue areas.  Several national and state agencies have risen to meet this  challenge and  now maintain GIS data centers that include downloadable mapping files and associated data. 

GIS Data Centers:

Caltrans Earth 


Caltrans Earth uses a clean, straightforward, and user-friendly interface to provide data on California’s transportation systems and other information.  The site allows users to preview the layers in a web mapping service, with the option to download the layer as either a shapefile, which can be opened in GIS-based mapping software, or a KML file for use in Google Earth.  Most of the layers in Caltrans Earth are linked to Caltrans’ database files and are simultaneously updated as new information is added to the internal files.


Caltrans GIS Data Library


The Caltrans GIS Data Library includes data on the physical environment, transportation, other infrastructure, political and administrative districts, cultural geography, and earth imagery.  The mapping layers are organized into a table that shows a link to the metadata, the form required to request access to the data, a sample image of the data, the extent of the data (State, District or County), when the data was last updated, whether it has been reviewed, the data topology (point or line), and data sharing restrictions. 


Cal-Atlas Geospatial Clearinghouse

California GIS Council

The Cal-Atlas Geospatial Clearinghouse manages sharing of geospatial data between California government agencies, partners, and stakeholders.  The site allows users to search for data layers, download data layers, upload data layers to share, and view maps and web applications using geospatial data.  The mapping layers include information on the description, source, and release date of data in the following categories: natural environments, administrative and political boundaries, planning and development, elevation, health, society, transportation, and earth imagery.


CNRA Atlas/Map Server

California Natural Resources Agency

The CNRA Atlas/Map Server provides users with the options of downloading free map viewing software, downloading geospatial data (ArcMap, ArcGIS Explorer, ArcGIS, JavaScript, Google Earth, ArcGIS.com Map), and viewing the data set in Google Earth.  The mapping layers and metadata are organized by the following categories: atmosphere and climate, base maps, boundaries, environment, geoscience, health, inland waters, location, military, ocean, society, and transportation.


National Atlas Mapmaker: Map Layers

United States Department of the Interior

The National Atlas Map Maker is a feature that allows users to assemble, view, and print maps based on data layers comprised of information from the National Atlas of the United States.  The map layers are organized by category in a table that allows users to view the data layer in the Map Maker or to obtain background information and download raw data from the map layer.  The map layer categories are agriculture, biology, boundaries, climate, environment, geology, history, map reference, people, transportation, and water.


ARB’s Geographical Information System (GIS) Library

California Air Resources Board

ARB’s GIS Library includes GIS shapefiles and metadata for county, district, and air basin boundaries; Federal air quality designations; State air quality designations; and California air monitoring stations.  The site also includes a link to all commonly requested maps, many of which include air quality management information by community and the option to download the data used to create the maps. 


The National Map Viewer

United States Geological Survey

The National Map Viewer allows users to preview and download data layers compiled by the US Geological survey.  The data layers are organized by base data layers (such as boundaries, topographic maps, land cover, imagery, and structures), other featured data (such as ecosystems, conserved lands, wetlands, and hazards), or user added content.  The Map navigation tool offers some of the data analysis and measurement functions found in GIS and Google Earth.


Geospatial Data Gateway

United States Department of Agriculture

The Geospatial Data Gateway is a catalogue of environmental and natural resources data from the Natural Resources Conservation Service, Farm Service Agency, and Rural Development.  The site has a user-friendly interface that separates the data download process into steps by identifying what location you want data for (“Where”),  the subject matter you are interested in (“What”), and the type of file, projection, extent, and method of delivery you want for your data (“How”).


Data and Maps

California Department of Fish and Game

The California Department of Fish and Game data and maps webpage includes a list of links for all departmental biological and geographic data.  The resources available include a GIS conservation data warehouse, an online biogeographic mapping tool, a data portal for fishing and habitat information, a document library, the California Natural Diversity Database for endangered species, the Vegetation Classification and Mapping Program for vegetation habitat, and the California Wildlife Habitat Relationships for animal habitat.


Free Data


The ESRI website includes free data available for download, including: base maps, demographic maps, reference maps and specialty maps.  Planners may be especially interested in the Census 2000 and Census 2010 TIGER/Line® shapefiles which include administrative and political boundaries, demographic information, landmarks, transportation routes, water features, and physical features.


Types of Floodplain Maps

California Department of Water Resources

The California Department of Water Resources has compiled a list of major floodplain mapping products developed by their office and the Federal Emergency Management Agency.  The maps include data for flood insurance, floodplains, and flood protection zones.

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