Lost in the Trayvon Martin story is the location where this all occurred: a gated community. While these are common in some places, particularly in Florida, one author explains the unique mindset in gated communities and how this might have contributed to the situation:

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.”

No matter the label, the product is the same: self-contained, conservative and overzealous in its demands for “safety.” Gated communities churn a vicious cycle by attracting like-minded residents who seek shelter from outsiders and whose physical seclusion then worsens paranoid groupthink against outsiders. These bunker communities remind me of those Matryoshka wooden dolls.  A similar-object-within-a-similar-object serves as shelter; from community to subdivision to house, each unit relies on staggered forms of security and comfort, including town authorities, zoning practices, private security systems and personal firearms.

Residents’ palpable satisfaction with their communities’ virtue and their evident readiness to trumpet alarm at any given “threat” create a peculiar atmosphere — an unholy alliance of smugness and insecurity. In this us-versus-them mental landscape, them refers to new immigrants, blacks, young people, renters, non-property-owners and people perceived to be poor.

This account lines up with academic research on the topic: gated communities are intended to be safe places. They are generally in the suburbs and residents move there to feel more secure. While not stated explicitly, these communities are meant to help keep issues like poverty, race, social class, and crime outside the walls and fences.

Here are the three best works I know on the subject:

1. McKenzie, Evan. 1994. Privatopia: Homeowner Associations and the Rise of Residential Private Government. New Haven, CT: Yale University Press.  

2. Blakely, Edward and Mary Gail Snyder. 1999. Fortress America: Gated Communities in the United States. Washington, D.C.: Brookings Institution.

3. Low, Setha M. 2003. Behind the Gates: Life, Security, and the Pursuit of Happiness in Fortress America. New York: Routledge.

One of the ironies revealed in these works is that these gated communities are rarely completely sealed off from the outside world. The ones that are tend to be the province of the wealthy and have very controlled entry points. For many gated communities, while there might be fences or walls, not all communities have manned gates and there are often multiple entrances into a neighborhood. So the gated nature of the community is more about a feeling of security than an actual sense that no unwanted outsider can get in.

In the end, gated communities do not necessarily lead to more violent action against outsiders. At the same time, the mindset in these communities is explicitly about safety and protection from the outside world.