At the beginning of the 1930's, many states like Oklahoma, Arkansas, Texas and Colorado were affected by the Dust Bowl (a storm of dust and sand). It causes a drought, because of it the soil was very dry and the plantations died.
The farmers couldn't stay in this situation because they earned no money so they chose to leave their farms and went to a place where they were supposed to live in a better way.
They decided to go to California. This state was known as The Land of Plenty. They had to drive for a long time on highway 66 which leaded from Chicago (Ilinois) to Bakersfield (California).
This journey was very tough because there were a lot of dangers like the lack of water and food, a run out of petrol and the heat caused by the sun and the drought.
They hoped to find a job and create a new life but they didn't know that they were not the only people to imagine that.
When they arrived in California, they were regrouped in migrant camp which looked like a slum. They had no money because of the journey and the difficulty to find a job so they had no solution to leave these camps.
As a conclusion, for the farmers the life in California was not as simple and moneyful as they thought.