Sources of Geographic Information

Arguably, one of the most difficult aspects of working with spatial data is finding it. Even when I collect my own data (in the field, from text, etc.), I always need contextualizing maps. These may be modern street or topographic maps or they may be historic maps or detailed topographic data from a source like LiDAR (Light Detection and Ranging; a.k.a. ALS or Airborn Laser Scanning). These maps can be used as investigative tools- to find certain types of places, to ask certain types of questions. Base maps, such as Google Maps, may also be the subject of the research (e.g., Zook and Graham 2007). And, sometimes you just need a base map to get oriented. Modern maps- There are many, many different types of base maps, but they fall into three broad categories:

1. raster-based satellite or aerial photos
2. vector based road and terrain maps
3. Hybrids of the above.

The most common modern map may be Google Maps. However, since Google is more than happy to use algorithms to benefit their business and those of their advertisers (e.g., Zook and Graham 2007), we highly recommend using open source mapping products. The most popular is OpenStreetMap (or OSM), which is based upon "volunteered geographic information." Of course, this also means that those who volunteered the information have an effect on the final data as well, in a manner similar to Wikipedia. Jumping ahead Harvard World Map Open Topography Atlas of Historical County Boundaries- http://publications.newberry.org/ahcbp/ IPUMS NHGIS- https://www.nhgis.org/documentation/gis-data David rumsey Library of Congress. Bibliographic references: Zook, Matthew A., and Mark Graham. 2007. “The Creative Reconstruction of the Internet: Google and the Privatization of Cyberspace and DigiPlace.” Geoforum, Theme Issue: Geographies of Generosity, 38 (6): 1322–43. https://doi.org/10.1016/j.geoforum.2007.05.004.