John Steinbeck called Route 66 the “Mother Road” in The Grapes of Wrath.
Steinbeck’s 1939 novel follows the Joad family as they leave Oklahoma and travel west during the Dust Bowl and Great Depression. In the book, Route 66 becomes the principal migration road toward California and is described as a route carrying families away from hardship.
The phrase helped transform a numbered highway into a powerful literary and cultural symbol. It suggested a road that gathered people together and carried them toward hoped-for opportunity.
Route 66 also had other nicknames, including the “Main Street of America” and the “Will Rogers Highway.” Those terms are genuine, but they are not the phrase associated specifically with Steinbeck’s description in The Grapes of Wrath. “Mother Road” remains the best-known literary nickname for the highway.