The novel tells the story of the Joad family as they prepare to leave their home in Oklahoma, journey to California, and attempt to make a new life for themselves there. The story is told in chronological order, arranged in chapters. The narrative is interrupted from time to time with the short chapters that direct the reader's attention away from the story of the Joads and focus instead on other people and places or develop short essays. These short interrupting chapters place the story of the Joads within the context of what was happening around them during this time. Eliminate the short chapters, and the remaining longer ones would be a straight chronological plot of the novel.
During the Great Depression of the 1930s, the setting of the novel, economic distress affected the entire country, but the Midwest was especially hit hard. During the Depression, great dust storms struck the heartland, literally blowing the farms away as the top soil was carried off in the wind. The Midwest became known as the Dust Bowl. Farmers could not grow crops and many became bankrupt; many family farms were repossessed by the banks when loans could not be paid. Also, during this time Eastern corporations bought up farms in the Midwest, pushed tenet farmers off the land, and farmed instead with machinery. Many thousands of poor and homeless American families headed to California where they hoped to find work in order to survive. It was a great migration, one of historic proportion.