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). 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 (like Google Maps, Apple maps, etc.)
3. Hybrids of the above.

  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.