Map Overlay is the newest of my free map tools, and it does one thing: it takes an image — an old county map, a plat, a land grant survey, a fire insurance plan, a hand-drawn sketch from a deed book — and lays it over a modern map at true scale, over the actual ground it describes.
All tools are available on my website at https://webjmd.com/mymapbuilder
With the map overlay tool, you position it by picking a few points you can recognize on both: a river bend, a crossroads, a courthouse corner, a bridge. Click the spot on your scan, then click the same spot on the modern map. Three or four good points is usually enough. The tool then stretches and rotates the scan into position and tells you, in feet, how far off it is likely to be — and it checks that honestly, by leaving each of your points out in turn and seeing whether the rest can predict it. If one point is badly placed, you will see it.
From there it is a real map. Fade the old map in and out with a slider, or drag a sweep line across the screen to see the same piece of ground both ways at once. Add as many images as you like — a whole run of Sanborn sheets, or every land grant in a neighborhood — and turn them on and off one at a time.
Everything happens in your browser. Your scans are never uploaded anywhere.
For research, the payoff is in the answers you cannot get from the old map alone. Whose land is that now, and what road runs through it? Which of these three creeks is the one in the deed? Is the house in the 1915 photograph still standing? Where, exactly, was the mill? Genealogy is full of places described in terms that stopped existing a century ago, and this puts those descriptions back on the ground where you can walk them.
When you are done you can save a single web page that contains the whole thing — maps, sweep, everything — and email it to a cousin or post it, with no software needed at the other end. If you want to work on it again later, simply upload the .html file that you saved, and it will open just where you left it. You can also save it as a file to open using Google Earth.
I have saved several maps using these four tools, and I have plans and ideas for many more. You can view the growing gallery of my maps, including the one for the 1915 Elkin Sanborn Maps, here:
These tools will be a big help for me in my research and in articles that I write. They provide ways to create visual interpretations of the places, events, and stories that we discover in old documents, and they are a convenient way to share what we learn.
More research and genealogy research on my website!
