The Grapes of Wrath is set in the American Southwest during the Great Depression, a period of dramatic economic downturn that lasted from 1929 to 1939. More specifically, the novel is set in Oklahoma, where the Joad family has lived for several generations, and California, the destination of many migrant families who have been evicted from their homes. A significant portion of the novel is set on Highway 661, also known as U.S. Route 66, which connects Oklahoma and many other parts of the American Southwest to California. Steinbeck’s depiction of this highway helps to establish this broader historical context:
HIGHWAY 661 is the main migrant road. 66—the long concrete path across the country, waving gently up and down on the map, from 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 land, from the thunder of tractors and shrinking ownership, from the desert’s slow northward invasion [...]
Many families such as the Joads travel down Highway 661 in hopes of finding employment in California, which has been promoted to them in handbills and newspapers. Steinbeck describes the highway as “the main migrant road,” underscoring its central role in this wave of migration. He describes the highway as winding through mountains, the “bright and terrible desert,” through more mountains, and ultimately culminating in the “rich California valleys,” providing a broad geographic overview of the region. The refugees, he notes, flee “dust and shrinking land” as well as the system of tenancy and mechanized farming that has made it difficult for many people to own their own property. Steinbeck, then, sets the novel in an environment of pronounced economic desperation and ecological collapse.