Abstract Across the nation, the debate over metropolitan sprawl and its impacts continues. A decade ago, Smart Growth America (SGA) and the U.S. Environmental Protection Agency (EPA) sought to raise the level of this debate by sponsoring groundbreaking research on sprawl and its quality-of-life consequences (Ewing et al. 2002; Ewing et al. 2003a, 2003b, 2003c). The original sprawl indices were made available to researchers who wished to explore the various costs and benefits of sprawl. They have been widely used in outcome-related research, particularly in connection with public health. Sprawl has been linked to physical inactivity, obesity, traffic fatalities, poor air quality, residential energy use, emergency response times, teenage driving, lack of social capital, and private-vehicle commute distances and times (Ewing et al. 2003a; Ewing et al. 2003b; Ewing et al. 2003c; Kelly-Schwartz et al. 2004; Sturm and Cohen 2004; Cho et al. 2006; Doyle et al. 2006; Ewing et al. 2006; Kahn 2006; Kim et al. 2006; Plantinga and Bernell 2007; Ewing and Rong 2008; Joshu et al. 2008; Stone 2008; Trowbridge and McDonald 2008; Fan and Song 2009; McDonald and Trowbridge 2009; Trowbridge et al. 2009; Lee et al. 2009; Nguyen 2010; Stone et al. 2010; Schweitzer and Zhou 2010; Zolnik 2011; Holcombe and Williams 2012; Griffin et al. 2013; Bereitschaft and Debbage 2013). In this study for the National Cancer Institute, the Brookings Institution, and Smart Growth America, we begin in Chapter 1 by updating the original county indices to 2010. As one would expect, the degree of county sprawl does not change dramatically over a 10-year period. Also, given their fixed boundaries, most counties become more compact (denser and with smaller blocks) over the 10-year period. Sprawl occurs mainly as previously rural counties (in 2000) outside metropolitan areas become low density suburbs and exurbs of metropolitan areas (in 2010). In Chapter 2, we develop refined versions of the indices that incorporate more measures of the built environment. The refined indices capture four distinct dimensions of sprawl, thereby characterizing county sprawl in all its complexity. The four are development density, land use mix, population and employment centering, and street accessibility. The dimensions of the new county indices parallel the metropolitan indices developed by Ewing et al. (2002), basically representing the relative accessibility provided by the county. The simple structure of the original county sprawl index has become more complex, but also more nuanced and comprehensive, in line with definitions of sprawl in the technical literature. In Chapter 3, we develop metropolitan sprawl indices that, like the refined county indices, have four distinct dimensions-- development density, land use mix, population and employment centering, and street accessibility. Compared to metropolitan sprawl indices from the early 2000s, these new indices 1 incorporate more variables and hence have more construct validity. For example, the earlier effort defined density strictly in terms of population concentrations, while this effort considers employment concentrations as well. The reason for developing metropolitan sprawl indices, rather than limiting ourselves to counties, is that metropolitan areas are natural units of analysis for certain quality-of-life outcomes. In Chapter 4, we conduct one of the first longitudinal analysis of sprawl to see which areas are sprawling more over time, and which are sprawling less or actually becoming more compact. To conduct such as analysis, we need to employ a new level of geography, the census urbanized area. In contrast of counties and metropolitan areas, urbanized areas expand incrementally as areas grow and rural tracts are converted to urban and suburban uses. The analysis shows that, on average, urban sprawl in the U.S. increased between 2000 and 2010, but that there are many exceptions to this generalization. Finally, in chapter 5, we develop compactness indices for census tracts within metropolitan areas. We know from the travel and public health literatures that there is a demand in the research community for built environmental metrics at the sub-county level, what might be described as the community or neighborhood scale. The appendices provide values of compactness/sprawl indices for census tracts, counties, metropolitan areas, and urbanized areas. Data are available in electronic form at http://gis.cancer.gov/tools/urban- sprawl/ 2 Table of Contents Abstract ......................................................................................................................................................... 1 Chapter 1. Updated County Sprawl Index .................................................................................................... 5 Update to 2010 ......................................................................................................................................... 7 Chapter 2. Refined County Sprawl Measures ............................................................................................. 11 Density .................................................................................................................................................... 11 Mixed Use ............................................................................................................................................... 12 Centering ................................................................................................................................................. 14 Street Accessibility .................................................................................................................................. 17 Relationship Among Compactness Factors ............................................................................................. 18 Composite Index ..................................................................................................................................... 18 Greater Validity of New Index ................................................................................................................. 20 Chapter 3. Derivation of Metropolitan Sprawl Indices ............................................................................... 25 Methods .................................................................................................................................................. 25 Sample ........................................................................................................................................... 25 Variables ........................................................................................................................................ 26 Results ..................................................................................................................................................... 28 Individual Compactness/Sprawl Factors ........................................................................................ 28 Overall Compactness/Sprawl Index for 2010 ................................................................................ 30 Discussion................................................................................................................................................ 32 Chapter 4. Urbanized Areas: A Longitudinal Analysis ................................................................................. 79 Methods .................................................................................................................................................. 79 Sample ........................................................................................................................................... 79 Variables ........................................................................................................................................ 79 Results ..................................................................................................................................................... 82 Individual Compactness/Sprawl Factors ........................................................................................ 82 Overall Compactness/Sprawl Index for 2010 ................................................................................ 83 Overall Compactness/Sprawl Index for 2000 ................................................................................ 84 Discussion................................................................................................................................................ 85 Chapter 5. Derivation of Census Tract Sprawl Indices ................................................................................ 86 Chapter 6. Conclusion ................................................................................................................................. 87 References .................................................................................................................................................. 88 3 Appendix A. County Compactness Indices for 2010, 2000, and Changes .................................................. 91 Appendix B. County Compactness Factors and Composite Indices for 2010 .......................................... 115 Appendix C. 2010 Metropolitan Indices ................................................................................................... 141 Appendix D. Urbanized Areas Compactness Indices 2010 ......................................................................