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Kimberly Powell

Historic Map Overlays in Google Maps

By June 7, 2009

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There's been a bit of discussion on genealogy mailing lists recently regarding historical overlay maps available for Google Maps. This technology has actually been in use for some time, with historic overlay maps first available for Google Earth back in 2006. The premise behind these historic overlay maps is that they are layered directly on top of current road maps and/or satellite images. By adjusting the transparency of the historic maps, you can "see through" to the map behind to compare the similarities and differences between old and new maps, and study the changes in your selected location over time. A great tool for genealogists!

More recently, the Google Maps API has encouraged a number of organizations, developers, and even individuals like you and me, to create historic overlap maps for the online tool Google Maps (nice for people who don't want to download the Google Earth software). 120 historical maps from the David Rumsey Map Collection, for example, were integrated into Google Maps last year. Additional historic map overlays you might want to explore, include:

  • North Carolina Historic Overlay Maps - Selected maps from the North Carolina Maps project
  • Scotland Historical Map Overlays - Ordnance Survey maps and large-scale town plans from the National Library of Scotland
  • Henry Hudson 400 - Historic overlays includes historical maps of early New York and Amsterdam as part of a project to celebrate the voyages of Henry Hudson.
  • Greater Philadelphia GeoHistory Network - Visit the Interactive Maps Viewer to view selected historic maps and aerial photographs, overlayed with current data from Google Maps. The "crown jewel" is a full-city mosaic of the 1942 Philadelphia Land Use Maps.
  • Singapore Historical Maps - This isn't an overlay, but combines a map with historic photos of Singapore places in an interesting way.

If you really love these historic overlay maps, you may want to download the free Google Earth software. There are many more historic map overlays available through Google Earth, than through Google Maps, including many posted directly by Google. You can find the historical maps in the sidebar section titled "layers."

Related: Make Your Own Google Map

June 9, 2009 at 1:58 pm
(1) Mark says:

I’ve done this myself before. However, one problem I encountered was that my overlay map, having been created hundreds of years ago, was a bit misshapen so that it would not line up to the current-day map boundaries not matter how I stretched or rotated. I don’t know how ancient mapmakers even came close given the tools they had then! Google does allow you to stretch your overlay horizontally or vertically, but that’s not enough. Ideally, I’d like to be able to pin several locations on my overlay to their actual coordinates on the current-day map and have Google dynamically stretch or distort my overlay image to fit correctly. There’s gotta be some image software out there that can do this, but I haven’t found any online.

January 9, 2010 at 9:41 am
(2) joey says:

What I do to get old maps to overlay as accurate as possible is to slice the image up into smaller pieces.

January 4, 2011 at 10:49 am
(3) Jamie says:

If you want to match old maps, the best you can do is to geometrically correct the older map to the Google Maps overlay. There will be a lot of discrepancies, but I would suggest using GIS tools like GRASS or MAPWINDOW (both free) to register the map overlay.

The trick is to match survey points, street intersections and other definitive map features. Don’t bother with river banks or anything that doesn’t have a corresponding “exact” (i.e. permanent feature) real world coordinate. Basically, make sure the feature then and now are as identical as possible. Make sure your ground control points are spread out across the map as evenly as possible to get the best results.

Use something like a bilinear interpolation or cubic convolution (3rd order polynomial maximum) to adjust the old map overlay to the newer map layer.

Good luck!

March 15, 2012 at 5:59 pm
(4) Amanda says:

There is such a thing for stretching along pins lines, but it is a part of Photoshop. I don’t know of any mapping software that has similar functions to it, but I am trying to create a layered historical mapping app. Did not know that users needed this accessibility and will try to build it in.


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