I was recently trying to geographically analyze census data from the mid to late 1800s. More specifically, I was looking at various families of the same surname who were living in the city of Philadelphia. I was trying to get a feel for the proximity of the various neighborhoods in which they lived and potentially a better feel for their relative socio-economic status. The problem was that I was unfamiliar with the neighborhoods and their locations within the city.
I was finally able to find an incredible mapping site that is almost too good to be true! The site is The Greater Philadelphia GeoHistory Network. On the site is an Interactive Maps Viewer tool. It contains various historic maps of Philadelphia and is designed such that they can be overlaid with a semi-transparent current Philadelphia streets map!
The map viewer works much like any graphics software that supports layers. In this case each layer is one of the maps. You are able to toggle the visibility of each layer/map independently as well as adjust it’s transparency with a slider control. You can also drag the various layers/maps up or down the stack.
The maps are very high-resolution, so you can zoom in close and see the details. In fact, the only drawback could be the load time if you have a slow internet connection. If you’re looking for historic Philadelphia maps, this is definitely a resource worth checking out.