Sources of burnable material within U.S. cities are analyzed. Based on a detailed evaluation of construction practices, storage of burnable contents, building function and layout, and density of buildings in city districts, we derive urban fuel load densities in terms of land use type and geographic location. Residential building fuel loads vary regionally from 123 to 150 kg m-2; nonresidential building classes have loads from 39 to 273 kg m-2. The results indicate that average U.S. urban area fuel loads range from 14 to 21 kg m-2.