Many of the photographs in the Philadelphia Department of Records City Archives’ collection are associated with a particular location. As photographers from the City’s Photography Unit traveled around Philadelphia capturing images of construction projects, school yards, busy commercial districts, and residential areas, they often noted the address or intersection where the photograph was taken. The other collections available on Philly
History.org- the photographs from the Philadelphia Water Department, the property maps from the Department of Records, and the historic maps from the Free Library- are also very geographic in nature and usually connected to a specific place in the city. Using the address or intersection associated with an image, a photo can be geocoded (mapped) to that location. Once a photograph has been geocoded in Philly
History.org, it can be found using the address or neighborhood search, making it convenient to view photos or maps based on the location where they were taken.Like the other photographs and maps on Philly
History.org, the collection of photographs from the Sesquicentennial International Exposition has a geographic element. The majority of the photographs were taken on the Sesquicentennial grounds in the area around the intersection of Broad Street and Pattison Avenue by present-day FDR Park and the stadiums. Many of the photographs depict buildings, attractions, or exhibits at the Sesquicentennial but do not give specific addresses or intersections where these places were located. Thanks to the staff at the City Archives, a copy of the Sesqui-Centennial International Exposition General Plan was located (also available in the “Sesquicentennial Exposition” article on Wikipedia
). This plan, published in the Sesquicentennial Promotional Booklet 1926, provided a map of many of the buildings on the Sesquicentennial grounds and showed the main roads that ran through the area- Broad Street, Pattison Avenue, Packer Avenue, and Moyamensing Avenue.While those four streets have remained the same, the rest of the area had changed considerably from the time of the Sesquicentennial in 1926 to the present. Streets that were created for the Sesquicentennial no longer exist, and areas that were open land in 1926 are now filled with roads and buildings. Using the Sesquicentennial General Plan, it was easy to see where the buildings existed in 1926, but the changing landscape made it much trickier to match those 84 year old locations with a Philadelphia street map from 2008. Since the geocoding system uses current street maps, it was necessary to find some way to sync the older map with the newer map in order to accurately geocode the photographs.
The solution to the problem came in the form of a piece of Geographic Information Systems (GIS) mapping software. One of the PhillyHistory.org software developers used the software to overlay the historic Sesquicentennial map with a current Philadelphia street map. To ensure that the maps had the same orientation, he found several points that were in the same location on both maps- the intersections of Oregon Avenue and Moyamensing Avenue, Broad Street and Packer Avenue, and Broad Street and Pattison Avenue. By lining up the two maps using these three intersections, a reliable composite map of the two images was made. To download a copy of the map, visit Azavea Commons. Azavea is the software company who created PhillyHistory.org for the Philadelphia Department of Records.
This two-layer map proved to be a valuable tool for geocoding the Sesquicentennial photographs. Using the historic map, PhillyHistory.org staff could see that the Nuremberg section of the Exposition was located south of Packer Avenue and several blocks west of Broad Street but could not determine a more accurate location. With the two-layer map, however, it was easy to see that the Nuremberg area was located precisely at what is now the intersection of 18th Street and Schley Street. Thanks to the assistance of the software developers and Archives staff, the PhillyHistory.org team was able to geocode a large number of Sesquicentennial photos, making them easy to locate on PhillyHistory.org and providing an illustration of how technology can help us relate the past to the present.