Residential density from e911 data plotted against residential density derived from census and GIS-buffer measures. E911 density values are based on actual geo-location of all residential structures in the state of Vermont. Both the x and y axis are on the logarithmic scale but actual density values are displayed. The identity line has an intercept of 0, a slope equal to 1, and represents an exact agreement between the two measures. Six highlighted school neighborhood sites are illustrative pairs in which residential densities based on census block group are comparable, but widely divergent when based on other measures.