TNC developed a digital version for the whole of David E. Brown and Charles H. Lowe’s 1981 map. Previously, GIS representations of this map were only available for its Arizona and New Mexico portions. Users: please note the relatively coarse source scale of the paper map (1:1,000,000) when using this digital version for analyses. A layer file (.lyr) which mimics the familiar color scheme of the paper map is also available.
