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. This may be modern street or topographic maps, it 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). Often, however, I also maps can be used as investigative tools- to find certain types of places, to ask certain types of questions. Sometimes you just need a base map to get oriented. NEED MORE HERE 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.