When John Steinbeck departed Stanford University for the final time in 1925, he left his roommate a note : "Gone to China. See you again sometime. Please free the chipmunk." His plan was to make like adventure writer Jack London and sail to the Far East on a freighter, but that voyage didn’t pan out.
http://noveldestinations.wordpress.com/2010/07/.
http://www.neabigread.org/books/grapesofwrath/readers-guide/historical-context/.