The Big Ten Academic Alliance Geoportal provides links to public GIS datasets, web services, and digitized historical maps from multiple data clearinghouses and library catalogs. The geographical area represented is primarily the Upper Midwest and Mid-Atlantic regions of the United States. As of December 1, 2016, the geoportal contains 3700 records that have been aggregated from over 30 different collections.

The majority of these records are from official state or local GIS clearinghouses, such as Maryland iMap or the State of Michigan GIS Open Data Portal. These government GIS clearinghouses typically provide datasets such as county boundaries, road networks, bodies of waters, geology, Public Land Survey System divisions, and various formats of aerial imagery. These kinds of datasets are especially useful as base layers for cartography or analysis.

The geoportal also contains records for scanned historical maps from university library collections. Many of these maps have been georeferenced, such as Purdue University’s collection of campus maps, and can be downloaded as raster files with embedded spatial information or accessed as a hosted image service. Although the other digitized maps are only available as plain image files, we have added bounding box coordinates for each of them within the geoportal. This allows a user to pan and zoom the map interface to limit their searches to a selected geographical extent. (Visit our Help page for guidance on different ways to search for items within the geoportal.)

Additional collections will be added to the geoportal on a continual basis. Upcoming records to be published include GIS datasets that have recently been made open to the public from individual counties and regional agencies. There will also be several large collections of digitized historical maps coming in early 2017.