AS a black man who has been mugged at gunpoint by a black teenager late at night, I am not naïve: I know firsthand the awkward conundrums surrounding race, fear and crime. Trayvon Martin’s killing at the hands of George Zimmerman baffles this nation. While the youth’s supporters declare in solidarity “We are all Trayvon,” the question is raised, to what extent is the United States also all George Zimmerman?

Under assault, I didn’t dream of harming my teenage assailant, let alone taking his life.

Mr. Zimmerman reacted very differently, taking out his handgun and shooting the youth in cold blood.

What gives?

Welcome to gate-minded America.

From 2007 to 2009, I traveled 27,000 miles, living in predominantly white gated communities across this country to research a book. I threw myself into these communities with gusto — no Howard Johnson or Motel 6 for me. I borrowed or rented residents’ homes. From the red-rock canyons of southern Utah to the Waffle-House-pocked exurbs of north Georgia, I lived in gated communities as a black man, with a youthful style and face, to interview and observe residents.

The perverse, pervasive real-estate speak I heard in these communities champions a bunker mentality. Residents often expressed a fear of crime that was exaggerated beyond the actual criminal threat, as documented by their police department’s statistics. Since you can say “gated community” only so many times, developers hatched an array of Orwellian euphemisms to appease residents’ anxieties: “master-planned community,” “landscaped resort community,” “secluded intimate neighborhood.”