Known by many names, and one of the original US Highway routes, Route 66 runs from Chicago to Los Angeles -- a total distance of almost 4,000 kilometers. It was a major highway for migrants going west before the second world war. It is now treated as a historical monument and preserved in many parts where it runs. It was decomissioned as an official highway sometime in 1985 as new and wider interstate highways were built.
It is still passable at present, paved and maintained and treated as a historic route. In southern Illinois, Route 66 has some of the most historical and most spectacular views.
Southern Illinois, USA
On Explore/Flickr Top 500, August 13, 2008