What is the participatory map, and when did it emerge? In the online world, we're in the middle of a renaissance of popular cartography, enabled by big data and the comparative cheapness of distributing graphic information on the web. Some of these maps-including some maps enabled by platforms like Google Maps, Open Street Map, or Ushahidi-are compiled by many individuals, working atop a digital infrastructure that enables the contribution of specific place-names, topographical features, social data, or real-time observations (for instance, of police movements, natural disasters, sexual assault, ecological contamination, or political corruption), all collected into a single interface that makes for easy analysis (