There is a Darwinian struggle taking place in the retail sector. It has been under way for quite a while, but the economic calamity of 2007–2009 accelerated the trend, sending dozens of once-healthy U.S. shopping malls into a financial downdraft. The strongest malls — the so-called fortress malls — are solidifying their dominant market positions while many weaker malls are trapped in a death spiral with limited potential for rescue.

The United States has long been described as “oversupplied” with retail assets, too much space for the traffic to bear. To put this in context, per capita retail space in the United States was estimated at 10 times that of Europe going into the recession.

The International Council of Shopping Centers calculates that there are about 1,500 regional and super-regional malls today, not to mention the open-air and special-purpose centers consumers encounter at every tur