In The Kite Runner, how and why does Amir come to United States?

This is a question that is answered for you if you re-read
Chapter Ten of this amazing book. It is quite clear that, now that Hassan and Ali have
left, and that the Taliban have seized power, Afghanistan is no place to stay for anyone
who has the resources to leave. The danger and autocracy of the Taliban regime, when
Baba was never that "religious" anyway, would have been terrible to him. Therefore,
Chapter Ten charts how they are smuggled out of the country. This of course is no easy
process. They face drunk Russian soldiers who threaten to rape one of the women until
Baba stands up for her and then a superior officer comes and lets them go. They face
other technical difficulties and face living in a basement for over a week with rats.
Eventually they leave smuggled out of the country in a fuel tank of a fuel truck which
does not allow the refugees enough oxygen. When they finally leave the tank, they
realise how the son of Kamal, another refugee with them, had died during the journey. In
a fit of grief, he steals a gun and shoots himself.

What is
important to note, especially for us in the West who have not experienced such
oppression as Afghanistan experienced under the Taliban, is the desperate nature of such
refugees who are willing to do anything to leave their home country. This should make us
think very carefully about how we welcome such political refugees into our
country.