Besides the obvious physical journey in the three books, Huckleberry Finn, Grapes of Wrath, and Catcher in the Rye, there is a psychological one also. It is a journey of coming of age. Huckleberry Finn discovers himself on the muddy Mississippi, as does Tom Joad during the migration to California, and Holden, although physically wandering through New York City, mentally explores the aspect of innocence, or rather, the lack of it, in society.
In all three books, the journey began when the main character were given freedom from a sort of prison of society. For Tom, it was a literal prison, but Huck escaped from "civilized" life and Holden, from the clutches of an upper class prep school. Whereas this escape released Holden from social responsibility and freed him to wander through the streets of New York aimlessly, Tom and Huck were burdened with a purpose. Huck's duty was to deliver Jim from slavery and Toms, to deliver his family and the rest of the immigrants.
Holden could stand back and observe other taking part in life, being "phony" and artificial. In The Catcher in the Rye, Holden's role was to simply observe the falseness of society; he did not really try to change this. Tom Joad, on the other hand, recognized the deliberate "play acting" and tried to be a leader, a role model for others. This is clearly recognizable upon his symbolic transformation into Jesus by the end of the book. Huck Finn, too, cleverly helped the naÃÂ¯ve and innocent girls get their money back in the incident with the King and the Duke.
The incident that triggered this psychological expedition was similar in all three cases. Tom began his symbolic change from "disciple" to "Jesus" upon the death of JC. Holden lost his innocence and...