First, Rural and Suburban areas promote fear:
In an open city...people of different colors and incomes must negotiate their mutual fate together. In some respects, they learn to value one another more highly, and social networks are expanded. In socially isolated environments [such as gated suburbs], social distance leads to stereotyping and misunderstanding, which in turn leads to fear and even greater distance. A resident in one of our [suburban] focus groups exemplified this dynamic when she told us that she never left her downtown San Francisco office building, even for lunch, for fear of people on the streets. Her building is located on a central street of department stores and offices, populated at lunch hour mainly by businesspeople and shoppers. But because it is a public space where anyone may go, it is too uncontrolled for her comfort, too unpredictable. Unlike her gated suburb, its openness increases the vulnerability she already feels to an unacceptable level.
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As one citizen told Constance Perin in her study of community and place in American life: "See, you have to understand the fundamental feeling in the suburbs is fear, let's face it. The basic emotional feeling is fear. Fear of blacks, fear of physical harm, fear of their kids being subjected to drugs, which are identified as a black problem, fear of all the urban ills. They feel [that] by moving to the suburbs they've run away from it, in fact, they haven't, in reality they haven't, but in their own mind's eye they've moved away from the problem." From Blakely & Snyder's Fortress America: Gated Communities in the United States via Bicycle Fixation
Not only are residents of vibrant cities usually less fearful of crime, they also tend to be less fearful of the big 'T': Terrorism, despite inhabiting much more likely targets than suburb dwellers:
We do not live behind gated communities and we do not have private security forces. We walk by alleys after dark and we dodge mentally unstable people to get to our subways and to make our bus connections. When you neglect the needy, we are the people that suffer. When the dispossessed and alienated riot, they riot in Newark, Detroit, and Watts. They do not riot in Topeka, Boise, or Crawford, Texas. From On Courage
Second, I think the simplistic cliché that the Left is all about hope, while the Right is all about fear holds a lot of truth. The Right Soothes Fear. The Right offers people the promise of security and order in what can feel like a world gone out of control. Witness McCarthy-era anti-Communist hysteria, which is very similar to the current hysteria over "Islamic terrorism". When facing something frightening, it feels good to have a strong, protective big brother.
Right-wing leaders know this, and they use fear as "a way of getting people to act against their own interests to work up hysteria and to get people to do terrible things to other people, because they’ve been made afraid." - Howard Zinn
Fear is one of our biggest challenges. Also see Can Fear be a Useful Tool for Progressives?