Here is an interesting claim: America has 40 million McMansions.

Americans, especially generations X and Y, want shorter commutes, walkability and a car-free existence. Which means that around 40 million large-lot exurban McMansions, built primarily during the housing boom, might never find occupants.

My guess is that this application of the term McMansion is quite misguided. Look at the original news story about these figures:

America has too many big houses — 40 million, to be exact — because consumers are shifting preferences to condos, apartments and small homes, experts told the New Partners for Smart Growth Thursday, holding its 11th annual conference in San Diego through Sunday.

Relying on developers’ surveys, Chris Nelson, who heads the Metropolitan Research Center at the University of Utah, said 43 percent of Americans prefer traditional big, suburban homes but the rest don’t…

He estimated that this demand suggests a need for 10 million more attached homes and 30 million more small homes on 4,000-square-foot lots or less. By contrast, demand for large-lot homes is 40 million less than currently available.

There is no explicit mention of McMansions in this original story. There can’t really be 40 million McMansions. In 2000, there were just under 70 million total detached housing units. So roughly half of all American houses are McMansions? Also, there are 40 million houses in the exurbs? (You may have to define all suburbs as exurbs to get close to this.) At the same time, one could argue that the average new home, around 2,400 square feet is still too big for what many Americans want. But, a home at the average or even slightly over is not automatically a McMansion.