History maps

OpenHistoricalMap (also spelled Open Historical Map and abbreviated OHM) is an online collaborative mapping project developing a historical map of the world using OpenStreetMap technology and processes. Whereas OpenStreetMap only includes data about the present day and deletes data as it becomes outdated, OpenHistoricalMap welcomes historical data and preserves multiple copies of a feature as it changes over time. The OpenStreetMap community views OpenHistoricalMap as an outlet for keeping outdated names out of OpenStreetMap, where they could cause misunderstanding.