The mapping and analytical capabilities of GIS technology have provided a national conservation organization with the tools needed to estimate the dollar value of U.S. urban tree cover at over $40 billion. The estimate suggests every city should learn about their local environment and invest in its management. American Forests, the nation's oldest citizen conservation organization, has developed a technique to map, measure, and analyze the value of urban ecology based on ecosystem services provided by tree canopy. The result is powerful information for city managers about local trees' contribution to storm water runoff reduction, air pollution mitigation, and energy conservation. American Forests' technique uses remote sensing and aerial photography to gather data. Scientific and engineering formulas provide detailed measurements of air, water, and energy benefits provided by trees. GIS technology developed by Esri and ERDAS provides the framework for the mapping and calculations. This presentation will demonstrate the technology and its application to specific areas of the country. The presentation will include representatives from American Forests, Esri, ERDAS, and Emerge.