The interaction between the Joads and the Wilsons, whose car has broken down along U. S. Route 66 in Chapter 13 exemplifies the theme of social commitment as the Wilsons aid the Joads after the death of Grampa while the Joads help repair the Wilsons' car. After the kindness of Sairy Wilson, the Joads suggest that they travel with them and divide the weight of their loads between the two vehicles.
Then, in Chapter 16, after traveling with the Joads for two days, the Wilson's car again breaks down. Tom offers to stay behind with Casy to repair the vehicle, explaining that it is important for the family to get to California as quickly as they can in order to procure jobs. "Casy can give me a lif' with this here car, an' we'll come a'sailin'." Al offers to stay with them, saying he can offer a strong back. Pa agrees, but Ma is worried about breaking up the family:
"What we got lef' in the worl'? Nothin' but us. Nothin' but the folks....An' now, right off, you wanna bust up the folks---"
Then, Tom and Ma agree that the Joads will go a ways and camp; then, Tom can drive the truck to get the part that the Wilson's need. In this way, they help the Wilsons, but they also keep together the family, "the folks," the most important of social commitments. In these chapters, too, is the beginning of the motif of the shift from "I" to "we."