That’s a neat collection of graphics. I’m curious how bespoke the creation process is for each graphic or if this is something everyone just does in ArcGis or similar.
That last graphic about the Western US being the only other candidate is interesting because the two sides of the Rockies weren’t connected by a highway until the I70 over Glenwood Canyon was completed in 1992. Before its completion, the western and eastern halves of Colorado were practically different states and it took the interstate highway project half a century to get there because the terrain was so challenging.