Final answer:
Steinbeck's primary purpose for writing 'The Grapes of Wrath' was to highlight the struggles of American families during the Great Depression, advocate for community and collective strength, and critique the socio-economic conditions of the era.
Step-by-step explanation:
One of Steinbeck's primary purposes for writing The Grapes of Wrath was to shed light on the hardships and struggles of American families during the Great Depression, particularly those affected by the Dust Bowl in Oklahoma. Through the journey of the Joad family, Steinbeck emphasizes the importance of community and collective action, illustrating how individuals can find strength in unity and how sharing a 'piece of a soul' with others can lead to greater resilience in the face of adversity.
The story portrays the journey to California in search of a better life and implies that joining a larger social movement, such as communism at the time, could be essential for the betterment of all people. Through the narrative, Steinbeck also comments on the socio-economic conditions that drove families to such desperation, weaving in broader political and social critiques.