In this chapter, Steinbeck offers a detailed description of a turtle trying to cross the highway. The turtle crushes a red ant that crawls into its shell; similarly, the turtle itself is almost crushed by a sedan roaring down the road. A truck also almost hits the turtle; it sends the animal spinning "like a coin" off the highway. Undeterred, the turtle begins its slow journey again.
The turtle in this chapter is symbolic and foreshadows the plight of the migrants. Similarly to the migrant, it faces the hostile world but it is persistent and learns to overcome all problems.
Chapter 3 presents the story of the migrants in microcosm--in the turtle. In this manner, Steinbeck makes it clear that the migrants will encounter many difficulties in their westward journey but they will survive and establish themselves successfully in California.