Amazing things can happen when civic technologists try to use and improve city data - come hear the story of how an imperfect dataset led to the largest participatory urban forest mapping project in the United States. TreesCount! 2015 scaled a mapping tool developed by civic technologists TreeKIT into a platform that enabled more than 2,200 volunteers to accurately map New York City's more than 660,000 street trees, and culminated in the development the NYC Street Tree Map - a digital platform for collaborative management of NYC's urban forest.