Image sourced from original post by The World Bank.
Following the Haiti earthquake, the World Bank, Google, and several other entities made high-resolution imagery of the affected area available to the public. Over 600 individuals from the global OpenStreetMap (OSM) community began digitizing the imagery, tracing roads, building outlines, and other infrastructure, creating what quickly became the most detailed map of Port au Prince that had ever existed. Volunteers from 29 countries made about 1.2 million edits to the map, performing an estimated year of cartographic work in about 20 days. This effort catalyzed a rethinking of community mapping and open data within the World Bank and other international institutions.
Read the full blog post on the World Bank website.