The Mother Road

 The term for Route 66 as The Mother Road comes from John Steinbeck's classic novel  "The Grapes of Wrath".   In Chapter 12 he writes of the westward migration during the depression and dust bowl.  Here's the passage:

"Highway 66 is the main migrant road, 66 - the long concrete path across the country, weaving gently up and down on the map, from the Mississippi to Bakersfield - over the red lands and the gray lands, twisting up into the mountains, crossing the Divide and down into the bright and terrible desert, and across the desert to the mountains again, and into the rich California valleys,
66 is the path of a people in flight, refugees from dust and shrinking ownership, from the desert's slow northward invasion, from the twisting winds that howl up out of Texas, from the floods that bring no richness to the land and steal what little richness is there. From all of these the people are in flight, and they come into 66 from the tributary side roads, from the wagon tracks and the rutted country roads. 66 is the mother road, the road of flight."

An interesting side note on this migration.  While thousands  made the trip to California  expecting better times, most were greeted with  unexpectedly poor economic conditions and  the largest majority of travelers actually returned  back east.