While many Americans may have benefited from the effects of rapid sub-urbanization: large yards, proximity to open space, new schools, increased mobility, and the financial appreciation of home values, these benefits have not been universally shared. Professional planners acknowledge that the social, economic, and environmental costs of urban dispersion can be more effectively managed, if not avoided entirely. The nation is now experiencing a heightened concern over the social, environmental, and fiscal quality of our communities arising from development practices that aggravate the decline of many urban communities and older suburbs, congest streets and highways, accelerate the loss of natural resources and the deterioration of the natural environment, and limit opportunities for the retention and creation of affordable housing. Often these problems are simply and collectively labeled, "sprawl." In response, the Smart Growth movement emerged.