I stumbled upon a blog, called "Jim and Nate Do America" which outlines a motorcycle cross-country trip on US Route 20 in the summer of 2008. They provide a detailed map of their trip (embedded below) and also include a photo slideshow on their blog of pictures taken on their trip, with a day by day accounting of their experiences.
If you’re looking for something to read about the country’s longest road from the perspective of someone who took the long drive all the way from end to end on a motorcycle, "Jim and Nate Do America" is an entertaining read.
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The US Route 20 Blog homepage can be found here.