People decide where they want to live and where to work, and so,
it's just a "natural occurrence" that, is dictated by how people behave. It's not about the U.S. or any government entity "deciding" where people will live or work. It just happens, with time and circumstances dictating to the people.
However, the smarter people in society should be telling people, over and over again, how living in dangerous areas, will eventually takes it's toll in lives and damage to homes and other infrastructure.