A little under a year ago the British Library released over a million images on Flickr Commons “for anyone to use, remix and repurpose”. This huge collection of historical images was “plucked from the pages” of digitized 17th, 18th and 19th century books automatically using the “Mechanical Curator,” created by the British Library Labs project. The library hoped that people on the internet would help them sort through the images and cluster them into useful categories and that is exactly what has been happening. At this point volunteers have identified more than 3000 maps in amongst the million images: “Maps, found by the community from the Mechanical Curator Collection“. With these maps identified, the British Library then fed them into another of their crowdsourced projects, where members of the community used an online tool to georeference historical maps. If you find a number of points on a historical map and on a modern map, the computer can then “pin” the maps over a modern digital map or a Google Earth digital globe. Depending on the quality of the original surveying and cartography and the care taken by the georeferencers, some maps lineup better than others and most suffer from some level of distortion when flat maps are stretched over a digital globe. Even with these problems, it is a really powerful tool to see historical maps layered over modern maps. In recent months people have worked to georeference most of the 3000 maps, adding to the existing collection crowd georeferenced maps shared by the British Library in recent years.
All of these maps, and thousands more shared by other libraries around the world, including the massive David Rumsey collection, can now be found through the Old Maps Online Website. Because the maps have geographical information, you can search for old maps by simply zooming into a particular region of the world (the website automatically prioritizes local maps when you’re zoomed in close and regional, national and continental maps when you’re zoomed out). The right hand panel will show you a list of all the maps for that region and when you point your mouse over a map, the website shows you a rectangle of the area covered by this map. The coverage is strongest for Britain and the United States, but the website is open for other major archives and libraries to expand the number of maps for their country or region. Each library or digital collection have different restrictions of what you can do with the maps and frustratingly, not many of them allow you to download a high resolution version with the georeferenced information included. Some, the British Library included, do allow you to open the maps in Google Earth and most allow you to download a medium resolution copy for non commercial research and publications. Limitations aside, the Old Maps Online makes an unprecedented number of published and archival historical maps accessible to academic historians, students, local historians and genealogies. In the case of the British Library’s Flickr Commons collection, they’ve used innovative crowdsourcing to find, georeference and share thousands of maps they did not even know existed less than a year ago. This provides model to georeference the growing collections of digitized historical maps available online and creates really exciting possibilities for historical research and for people who just really enjoy exploring old maps.
For those interested in how historians will use the growing wealth of digitized historical maps, we’ve posted a recent public lecture by a leading historical geographer, Anne Kelly Knowles, called Vision in History. In this lecture, Knowles discusses her work on the early industrialization in the United States and on the Battle of Gettysburg, using a combination of historical maps and documents with useful geographic information.