I've posted some articles on auto trails from the San Diego Union newspaper in the auto trail articles section (http://www.americanroads.us/autotrailarticles.html).
I've greatly added to the number of articles regarding old auto trails. You can find them on my auto trails articles page (http://www.americanroads.us/autotrailarticles.html). These are mostly very old articles from the early 1910s. Some are on the Ocean-to-Ocean Highway, the predecessor to the National Old Trails Road, that was originally planned to pass through Yuma and into southern California. There are also numerous articles on one of the world's first desert rally raids, the Los Angeles (and San Diego) to Phoenix desert race that began in 1908. Many of the early racers of the Indy 500 and the American Grand Prize also took part in these races. It became evident while reading these that the topic of the road race was completely intertwined with the choice of the Ocean-to-Ocean Highway route into southern California. There are also some articles about Pathfinder Anton L. Westgard and his transcontinental explorations by auto. I'll be posting more of these and other articles soon, so keep looking back.
Steve
I just uploaded a 1915 article from Outing magazine called "The Trail of the Painted Posts." It's a tourist's description of the benefits, and occasional difficulties, of following the new named auto trails and their colorful pole markers in the Midwest. The article offers an excellent glimpse of what interstate auto travel was like in 1915.
The Trail of the Painted Posts (http://www.americanroads.us/articles/Outing_1915_11.html)
For more vintage articles visit my auto trails article page:
http://www.americanroads.us/autotrailarticles.html (http://www.americanroads.us/autotrailarticles.html)
Steve