What are the effects of the locals' hostility on the migrants like the Joads in The Grapes of Wrath?

In the most demonstrative of manners, I think that the
effects of the locals' hostility on the migrants helps to display another hurdle that
must be faced on their road to redemption and some semblance of happiness.  I think that
the desire to go out West represents a dream for the Joads.  In this lies the promise of
a better life because it is so vastly different from what they are experiencing.  I
think that in this there lies a struggle that is enhanced by the response of the locals
to the migrants like the Joads.  The struggle that they endure is added because of the
reaction of the locals, many of whom see the migrants like the Joads as threats to what
they have.  Steinbeck constructs the reactions of the locals to show how a sense of fear
has gripped everyone.  There is a fundamental disavowal of collective or communal aims
because of the fear that whatever little is possessed will be taken away by others.  It
is for this reason why the effects of the locals' hostility helps to solidify Tom into
embracing what Casy had been preaching as well as seeking to create a vision of what
should be in the world as opposed to what is.  The inertia and resistance that the
locals demonstrate do not wither his resolve, but actually enhances and strengthens it. 
Additionally, it is this reaction that helps to forge Ma's strength in keeping her
family together, intact for the pursuit of the dream of happiness that animates her
sense of being in this world.