Milkman is on a mission to prove to not only Guitar but his father and sisters that he is his own person. He has been a follower his whole life and a bystander, just letting things happen and being nonchalant about everything. His father's reputation casts a big shadow over milkman and gives everybody in his town a impression on him before they even meet him. So when Milkman finally made a decision for himself to fly to Pennsylvania on his own to find Pilate's bag of gold. While it is his father who wants it this was the first step in Milkman's journey of finding himself.
Yes, that's what I believe this whole journey is about. Milkman wants a name, not one that was made up, one that is truly his. As he enters this small town in rural PA, he finds out more about his family, he finds out good things bad things, but the most importantly he finds out he has roots. He learns that his family has history before his grandfather and father. He finds out that they touched lives in a positive way rather than the negative impact back in Michigan. As Milkman finds out more about himself and his family he also starts to lose the weight of luxury and takes his first steps away from his father. While he's been living his whole life trying to be the opposite of his father, while he was not walking directly behind his dad he was walking next to him in a parallel line. Now he's starting to diverge and go his own way. After he finds out that the gold isn't in the cave like his father said it might be he heads south to Virginia.
The funny thing about rainbows is that technically they never end, you may see it ark down and kiss the horizon but if you were to walk there it would turn out to end in another place. Milkman might soon find this out, and he may never find the gold at the end of the rainbow or maybe he's finding it bit by bit...just not in a literal sense. Thoughts?