Open Historical Map

OpenHistoricalMap (OHM) is an interactive online collaborative mapping project that aims to create the world's most comprehensive historical map using OpenStreetMap technology. Unlike OpenStreetMap which only shows present-day data, OHM preserves and displays historical geographic data throughout different time periods.

You can contribute by going to the main map, zooming in to a place of interest, and clicking the 'Edit' button. The editing experience is very similar to OpenStreetMap. Users can add historical data, edit existing information, and help improve the accuracy of historical maps.

OHM focuses on mapping historical geo-objects such as shorelines, political boundaries, buildings, roads, and points of interest. It maintains multiple versions of objects as they change over time, but does not collect data on historical events per se.

Contributors include members of the OSM community, academic dataset providers, historical societies, digital humanities students and faculty, armchair historians, open data providers, open data enthusiasts, and various other map data creators.

While OpenStreetMap only includes current data and deletes outdated information, OpenHistoricalMap specifically welcomes and preserves historical data, maintaining multiple versions of features as they change through time. It serves as an outlet for keeping historical information that doesn't belong in OpenStreetMap.

The main project website offers two visualization styles for the historical data: a functional Historical style and an artistic Woodblock style, both displayed through vector tiles.