- Smart Growth America (SGA) defines sprawl as "the process in which the spread of development across the landscape far outpaces population growth." This type of development is marked by low-density, single-story buildings where various land uses--residential and commercial, in particular--are segregated from one another. The prevalence of single-family homes located far away from shopping centers, schools and places of work creates over-reliance on the private automobile for transportation. Places such as Riverside, California, and Greensboro, North Carolina, are the most sprawling, according to SGA, while New York City, San Francisco and Portland, Oregon, are among the most compact.
- In sprawling parts of the country, people tend to drive more. SGA estimates that in the ten least compact metro areas in the United States, there are 180 cars for every 100 households. In the most compact places, excluding extreme examples like New York City and Jersey City, there are 162 cars for every 100 households. SGA found the excess driving in the least dense places accounts for increased vehicle emissions, more fatal car accidents and lower rates of walking and public transit use. The Sierra Club points out the average American worker spends what is equal to 55 eight-hour workdays behind the wheel of a motor vehicle each year.
- A litany of research released in the early 2000s links suburban sprawl to negative health outcomes. One of the most influential studies was prepared by Dr. Reid Ewing and his colleagues, associated with the University of Maryland, Rutgers and SGA at the time. Ewing's work showed individuals in sprawling counties weighed more than their counterparts in dense places, presumably due to decreased physical activity associated with car dependence. Other data from Ewing and SGA show an association between living in sprawling places and hypertension, or high blood pressure.
- Critics also finger car dependence for causing so-called social isolation in sprawling areas. Among the most vocal promoters of this notion is author James Howard Kunstler. His books, including "The Geography of Nowhere," are required reading in most university urban planning classes. Kunstler contends that excess driving keeps people off of the streets where they might interact more with their neighbors. Echoing the sentiment first made popular by Jacobs in 1961, Kunstler, as of March 2010, travels the nation arguing that sprawl erodes a neighborhood's sense of community.
- According to the Sierra Club, sprawl and its attendant car dependence accounts for a portion of the 12 billion or so pounds of pollutants produced by motor vehicles each year. The Sierra Club also contends suburban sprawl developments sacrifice over 1 million acres of parks, farms and open space yearly.