Basically American cities stopped growing at a rate sufficient to handle the boom in people in the mid-late 20th century. Now there is huge demand on cities to house people affordably but the entrenched powers that be in these areas prevent the necessary development through tools like zoning or bureaucracy.

The whole system is basically fucked. Sigh.

I was actually looking for this http://jakeseliger.com/2015/12/27/why-did-cities-freeze-in-t... and we had an interesting discussion going at https://news.ycombinator.com/item?id=10798352

Both might still be a bit too rumbling. If you want the least rambling, the Economist is almost always the way to go:

http://www.economist.com/blogs/freeexchange/2015/04/land-val...