Stephen Von Worley, on his website http://www.datapointed.net, has mapped out a very efficient route to visit every state in the Lower 48. With an average speed of 55mph and time for stops, Von Worley calculated that one could drive the route in 124 hours. The 6813 mile trip starts at South Berwick, Maine, and ends in Taft, Montana.
Adding flights to Honolulu and then Anchorage, and you can visit all 50 states in a total travel time of around 160 hours.
This post comes via Knoxville, Iowa