What are some political and social changes that the Joads go through in The Grapes of Wrath?

The novel takes place during The Dust Bowl in the 1930s, which affected 2.5 million people in the Southern Plains region of the United States. It is one of the worst human-caused ecological disasters in history. Dust storms raged across the plains, wiping out crops, killing livestock, and causing respiratory failure and and other health issues. The novel takes place during the Great Depression (1929-1939), one of the worst economic downturns in the history of the industrialized world.
The Joads lived a comfortable farm life until the Dust Bowl destroyed their crops, their farm was repossessed, and they were forced to default on their bank loans. The Joad family and thousands of other migrants from the Southwest move to California, where they struggle with basic needs and a stagnant job market. The Joad family are migrant workers who work in government migrant camps. They work farm land in exchange for crops, bouncing from one job to another. The camp conditions are crowded and dirty, filled the poor and hungry.
Steinbeck wrote The Grapes of Wrath call attention to the lives of the poor through social realism. His novel functions as a report on the state of American society. At the time of publication, Steinbeck's novel was labelled socialist propaganda, and the FBI classified him as a threat to ideals of capitalism. Steinbeck establishes a picture of American society which includes his take on the lives of American people.