Building large amounts of high density housing, which San Francisco and Oakland do already have, makes no sense if the people living there cannot get anywhere.

FORBES: Silicon Valley Is Stuck In An Uncanny Valley Of Density

Stephen Walters, chief economist at JP Morgan, said there was some "static" in the data with volatility in high density housing data in New South Wales helping to skew the result, but added it was still clear that a downtrend is underway in housing.

WSJ: Australia Housing to Drag on Growth

Yet as suburban construction ended, cities continued building high-density urban housing--sometimes encouraged by city subsidies.

FORBES: New Geographer

The biggest move came in 2004, when Romney signed legislation, dubbed Chapter 40R, providing funds to towns and cities that agreed to allow more high-density, multi-family housing.

FORBES: Mitt Romney Says He May Ditch HUD