Doesn't mention a very important factor: the amount of stuff Americans own. All that stuff needs to get put somewhere. Over the decades, Americans have decided that it goes into garages (pushing parked cars out onto the street) and bedrooms (increasing the demand for "spare" bedrooms).

It's a real eye-opener to walk through residential neighborhoods and notice that most garages with open doors can't actually be used as garages anymore because of all the stuff crammed into them. Oddly enough, this phenomenon seems most pronounced in poorer neighborhoods, where hardware parked on the street (boats, RVs, and even derelict cars) leads to a "wall of vehicles" effect.

The flourishing self storage market is further evidence that even supersized houses aren't enough to satisfy demand to store ever more stuff.