Former Azavea software developer, Michael McLarnon set out to develop an application called a "Historic Geocoder", through which he aimed to address the difficulties of geocoding historic pieces of information with a ‘current’ set of location data. The project would consist of three parts: a) a record of street name changes; b) a database of street segment changes; and c) software to enable time-based geocoding.
By recording not only where current streets are and what they are named, but also where streets were in the past and what they used to be called, the Historic Geocoder would provide us with the ability to geocode based on both space and time. Instead of only entering a location, a user would be able to enter a location and a date. The system would then locate where the historic address was during that time period on a current map. While Michael is no longer with Azavea, we are hoping to continue expanding on his efforts.
Historic photos are not the only records with potential historic address problems. Surveys, censuses, and legal records all use addresses to describe locations. Being able to geocode these locations with relation to time is a very important first step towards the analysis of these data.
Michael McLarnon, Heather Newlin, and Jason Hutchins, "PhillyDotMap: The Shape of Philadelphia," Mapping Historic Streets. (Philadelphia, PA: University of Pennsylvania, ScholarlyCommons: Repository, 2009).