How the History Aerial Photo Comparison is Put Together

1. Download imagery from USGS Earth Explorer (Free account needed to download; most interesting is to Single Aerial Photos) and USGS Historical Topographic Maps
2. Use the QGIS Georeferencer to add control points and re-project the map.
3. Export two matching area/scale images from QGIS showing the before and after
4. Use the jQuery TwentyTwenty Plugin to provide the slider for your browser