Previously, I mentioned my recent visit to the National Archives researching Cobb County history. Today I want to share another discovery from this trip: 1930s Aerial Photography!
The oldest Cobb County aerial photography I have found is not from the archives of our country’s Military, Defense, or Information groups. Surprisingly, it comes from the United States Department of Agriculture, specifically the Agricultural Stabilization and Conservation Service (ASCS). This department, started in the 1930s, was one of the earliest groups experimenting with combining new technologies of airplanes and photographic equipment. The results are interesting as they provide some of the earliest records of Cobb County crop coverage.
The National Archives has 77 photographs of portions of Cobb County from 1934. Kennesaw Mountain, Marietta, the Chattahoochee River, and the Concord Covered Bridge Historic District are all covered.
Photograph #470 has a great view of the Concord Covered Bridge Historic District in 1934:
You can see the Concord Covered Bridge, the grist mill dam creating quite a pond, the long shadow of the Silver Comet railroad trestle, and the clearing for the Ruff Cemetery. The Concord Woolen Mill is standing with the roof still in place. Within a few years of this photograph being taken, the roof will fall in and trees begin to grow inside the mill.
I digitized the map with a computer and scanner, then geo-referenced it using modern Cobb County images.This process, sometimes called “rubber-sheeting” involves identifying a handful of identical points on each image.
After this process, you can super-impose a photograph or map on top of a current map for comparison:
Here is a view of Marietta in 1934:
And here is Kennesaw Mountain:
One interesting aspect of aerial photography is that often multiple images are made as the aircraft flies over the target, resulting in some overlap. This overlap creates a stereoscopic view of the ground surface. Using special software, you can manipulate these multiple images to extract digital elevation model (DEM) information. If you combine the original imagery with the elevation data, you can explore the photographs in 3D from a point of view on the surface. Here is an example of the view you might have experienced driving down Concord Road in the 1930s toward the Covered Bridge:
There are several more cans of film covering Cobb County from the late 1930s and early 1940s I would like to scan on my next return to Washington, DC.