摘要：1 online resource (xiii, 250 pages) : illustration
Sprawl is significant, low-density development taking place at the periphery wherein there exists limited infrastructure and public services. It has been the subject of much research, due to its widespread occurrence. Previous empirical studies of sprawl measurement had three significant weaknesses: 1) incomplete coverage of the geography being measured; 2) an absence of regional differences in the density variable, and 3) a lack of exclusion of undevelopable lands when calculating the density of an area. In an effort to overcome these shortcomings, this study: 1) measures sprawl for all 3091 counties in the US using economic areas (EA) to group counties; 2) uses variable densities (locally-determined cultural densities) in the sprawl calculation; and 3) calculates "refined densities" for all states and counties in the US by excluding undevelopable lands from the density calculation. Further, the research results included here are compared with those of Rolf Pendall (1999), Robert W. Burchell (2002), and Reid Ewing (2003b), in order to ascertain the impact of their more comprehensive measurement methods on sprawl measurement results. Based upon accurate variable densities, one of six county land use types (urban center, urban, suburban, rural center, rural, undeveloped) is assigned to each US county; a sprawl/non-sprawl is then determined for each county. As a result, out of all 3091 US counties, 492 experience sprawl development during the 2000 to 2020 time period. Over 80 percent (or 396 counties) of these 492 sprawling counties are rural or undeveloped counties; the remaining one-fifth are developing suburban and rural center counties. With no exception, the "refined density" of an individual state is greater than its "gross density." About 65 percent (or 32) of US states have "refined densities" that are at least 1.2 times their original gross densities. Several conclusions can be drawn using the comparative analyses included here. First, sprawl research must focus on the nation as a whole, or on select component regions. Second, variable density is crucial to the accurate calculation urban versus rural counties nationally. Third, developable land must be employed when calculating variable density (i.e. undevelopable lands must be excluded from the density calculation).