Why go downtown at all?

 A video from 1965 talking about urban decay in St. Louis.

The suburbs surround what we have long thought of as the central city, the core area, but what will happen to the surrounding belt of suburbs if this core simply disintegrates and then
vanishes? Could the suburban belt just go on expanding forever leaving a bigger and bigger circle of nothing much in the middle, a bigger and bigger hole in the doughnut?
--http://nextstl.com/2015/12/why-go-downtown-at-all-presaging-urban-decline-in-st-louis/