Old maps online: enabling global access to historical mapping

Over the last thirty years, map libraries worldwide have scanned some hundreds of thousands of historical maps from their collections, and most are viewable online via the world-wide web. However, maps remain difficult to access because they are individually hard to find: a user needing a map of a given location needs to know which library or libraries to search, and library search interfaces generally require knowledge of map titles: there has been no “Google for old maps”. We review previous attempts to create such a federated search portal and then explain how our new portal at www.oldmapsonline.org differs. One feature of our approach is that we prioritize rapidly achieving critical masses of content and usage over long-term sustainability. This means that we are assembling metadata from map collections essentially manually, maximizing the number of libraries who can participate. One longer term aim is to encourage use of sustainable web addresses for historical maps, Universal Resource Identifiers rather than URLs, which do not contain references to particular pieces of software, or reflect particular transitory arrangements of library web sites. A second long term aim is not to create a specialized automated metadata harvesting system for maps, but to ensure that the systems which major libraries are anyway putting in place for their overall collections do include the spatial coordinates needed to make content geographically discoverable.