In this paper we report an analysis of 118 urban areas sampled from the 12 largest metropolitan regions in the US. We deal with familiar measures of block size, street density, intersection density and distance between intersections. We also introduce two new variables, Reach and Directional Distance. Reach is the aggregate street length that can be accessed from the midpoint of each road segment subject to a limitation of distance. Directional distance is the average number of direction changes needed in order to access all the spaces within reach. We provide parametric definitions of these variables and implement their computation using new software which runs on standard GIS representations of street center lines.