This looks to be required reading...

Amazon.com: Route 66 Adventure Handbook (Adventure Pack): Explore similar items

The Route 66 Adventure Handbook unlocks the best of what Route 66 has to offer--including Colorful History, Roadside Treasures, Natural Wonders, Vanishing Americana, and Amazing Adventures. Includes photographs.
Essential to any Mother-Roader's tool kit, this "Adventure Pack" edition includes a set of 4 Full-Color postcards depicting some of the most famous Route 66 landmarks.