In 1926, highway planners laid out a ribbon of roadways connecting the nation. One of the most important wove its way across eight states, from the cities of the heartland to golden California. In The Grapes of Wrath, John Steinbeck calls it "the Mother Road." Route 66 has become a legend, celebrated in books, movies, works of art, and popular music. The interstates could not kill it. As "the Main Street of America," Route 66 had to pass through "the...