a rather handsome map of the routes, as opposed to the interstates, of the United States designed to resemble the schematic of a subway map. Cameron Booth, an Australian designer, compiled the image (here at full size), which should be viewed together with the similar map he created using the interstates.

These are serious undertakings, as Mr Booth notes on his blog when describing his most recent effort:

I have to say that without a doubt, this is the most complex network that I have yet attempted. Not only are there far more numbered routes than in the Interstate system, but there are also historical extensions and branches of many routes to consider. In some cases, numbers that were used once were reused in different parts of the country (see U.S. 48, which has been used for three completely separate roads!). I have attempted to show these historical roads as thinner route lines “behind” the main network, including the most famous U.S. highway of all – Route 66, which gets special treatment, being solid black in colour.

This might be too much map geekery for you; I think it's superb. (Hat tip)