Maps of Dreamland

This map shows the coverage of the US with the  USGSTopo maps available online in PDF format.  The colors show the year the maps were created.  What is more interesting is that there is one void in the lower 48 states, the white patch in southern Nevada.  

Zoom in to show the region without current USGS topo maps.  Note the red urban area in the SE part of the map, which is part of Clark County, or urban Las Vegas.   Nothing crazy going on there, beyond the normal for Las Vegas.  To the north is heaven (one of the quads in actually named Heaven's Well), some of which is really hard administratively to get into--I've tried, and have been in parts of it.  Some of it also very open federal land belonging to the Desert National  Wildlife Range, protected only by few roads and rugged topography.  The easternmost row of missing quads includes the Sheep Range, where I mapped for my PhD, and have led a series of field trips to see the spectacular geology.   I had previously discovered that this much of this area lacks the high resolution imagery which covers most of the rest of the US.