[Retric]

New infrastructure is often vastly cheaper to build than existing infrastructure is to maintain and adapt. So, letting some city's die IMO has value.

DC is probably the classic example of a city best abandoned. We already moved capitals once, and frankly we would be well served by doing so again. DC was designed to be hard to move around in and guess what, it's hard to move around in.

Detroit, while not nearly as bad as some, really does not fit the needs of a modern population.

PS: It can literally be 10 times as expencive to build infrastructure in existing city's.