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The two links above take you to Pennsylvania and North Carolina GIS data portals. Once in a state GIS data portal, you have access to many types of GIS information, from simple vector data, such as roadways, to complex raster data in the form of detailed aerial photography. In addition to individual state GIS data portals, make sure you check other state and local sources such as the Department of Transportation, Department of Environmental Protection, and local government GIS data portals.
Why we need it
Sometimes local GIS information is not available from Federal GIS databases, so we need to look elsewhere to find data. Sources for this information can be found on most state, county, and municipal GIS websites. Depending on the level of government accessed, the type and amount of GIS information available will vary, with state GIS websites having the most available data and municipalities having the least, depending on size. Many times, local GIS data may be more up-to-date and more specific to the area you want to study. The combination of federal, state, county, and municipal GIS data sources gives the best opportunity to find the data you need for a specific project.
Where to find it
- The University of Arkansas, as an example, has compiled a clearinghouse for individual state GIS data. This clearinghouse provides access to individual state data that includes many of the topics we outlined above.
- Individual county and municipal GIS data can be accessed through county and local government GIS Internet sites. In addition to the types of information outlined previously, land parcel information and current aerial photography may be available for download from county and municipal geospatial web links. Some of these sites may ask you to register for downloading data. I have registered for many of these sites at no cost.
- Another example of a state geospatial data clearinghouse can be found at the University of Oregon. The UO Libraries maintains a State-by-State listing of geospatial data resources.
- An example of county data can be found here for Union County, NC.
- Here is an example of available California County GIS data.
Tell us about it!
Do you have a suggestion or two for additional data sources? Use the Discussion Forum to share your suggestions with the class!