Sprawl Rankings Reveal Health Benefits and Cost Offsets in Compact, Connected U.S. County and Metro Areas

As for the health outcomes, the report found that compact and connected areas have 0.67% lower rates of heart attack hospitalizations, likely due to greater opportunity for physical activity, including walking, and better access to healthy food and preventative care. 

The analysis also found that a 10% increase in index score corresponds to a 7.6% reduction in total vehicle-related fatalities and an 18.4% reduction in pedestrian-related fatalities. It also found that people in more compact counties have lower exposure to vector-borne diseases such as Lyme disease. The analysis finds that a 10% increase in county index reduces the risk of Lyme disease by 21%.  

As for quality of life, the report found greater opportunities for youth to thrive with better access to education and employment in areas with higher index scores. The researchers found that a 10% increase in county index score reduces the rate of disconnected youth by 3.4%. For example, a person aged 16–24 in an average household in Baltimore County, MD, (index score: 87) is 28.3% more likely to experience disconnection than a child in the same household in Baltimore City (index score: 181).   

For medium-sized metro areas—or areas with a population between 500,000 and 1 million—the Madison, WI, area, ranks as the most compact with an index score of 126.3, while the metro areas of Fayetteville, NC, and Baton Rouge, LA, with scores of 60.0 and 62.5, respectively, are among the most sprawling.  

Among small metro areas with a population under 500,000, Trenton-Princeton, NJ, is the most compact, with an index score of 152.2, and Hickory, NC, is the most sprawling, with a score of 57.9.  

Urban sprawl has been debated for decades. Anti-sprawl groups argue that more compact and connected metro areas are better for health, environmental, social, and economic outcomes. Those who support more development in outer areas argue that compact development makes housing harder to build and less affordable.  

In recent years, housing affordability—the ability to pay for housing and other costs associated with the housing location, such as transportation and energy, with available income—has been a priority for both consumers and policymakers and a focus in local and federal elections. Housing is considered affordable if it takes 30% or less of after-tax income. Transportation is considered affordable if it takes 15% or less of income, and energy is considered affordable if it takes 6% or less of income. In more sprawling areas, housing costs tend to be lower, but transportation and energy costs are significantly higher. In more compact areas, housing costs tend to be higher, but transportation and energy burdens are lower.   

Overall, as index score increases, transportation and energy costs decline faster than housing costs rise, creating a net decline in the combined costs of housing, transportation, and energy in compact counties.  

According to the report, a 10% increase in an area’s index score increases the housing cost relative to income by about 1.2%. At the same time, a 10% increase in a score decreases transportation costs by about 4% and energy costs by 2.7% relative to income. This means compact and connected areas are more affordable when combining the proportion of income spent on housing, transportation, and energy costs. 

For example, an average household in San Francisco County (index score: 252.6) spends 47.3% of its income on housing, transportation, and energy costs, while an average household in Riverside County, north of San Diego (index score: 61.7), spends 51% of its income on the same items. The report includes other examples.  

“Before we can advocate for or against sprawl, we must understand how and where sprawl is occurring and how it impacts everyday life and health,” says Shima Hamidi, PhD, MSc, Bloomberg Associate Professor of American Health in the Bloomberg School’s Department of Environmental Health and Engineering and the report’s lead researcher. “The findings confirm that the way we design our communities has far-reaching consequences for health, affordability, and social connection.” 

The indices are available for 233 metropolitan areas, 995 urban counties, and 64,444 census tracts from 2020 in the lower 48 states and the District of Columbia, covering 281 million Americans or 85% of the U.S. population. The analysis used data from the Department of Energy, the Department of Transportation, the Department of Housing and Urban Development, the Centers for Disease Control and Prevention, and the U.S. Census Bureau.  

The report can be used by cities and local governments to consider planning processes and policies that create more connection and transportation choices with walkable and livable neighborhoods. The researchers provide recommendations—including building higher-density developments, enhancing neighborhoods, fostering strong urban centers, and promoting accessible and connected streets.  

“We need to look at how we are building our neighborhoods to meaningfully improve these outcomes,” says Hamidi. “This report can provide community planners, government officials, and policymakers with foundational insights into how to improve land use and zoning policies, prioritizing walkable, mixed-use, and transit-accessible development.” 

“Who Sprawls the Most? Mapping Urban Sprawl and Assessing Its Impact on Everyday Life” was written by Shima Hamidi, Seyed Sajjad Abdollahpour, Ebrahim Azimi, and Reid Ewing. It was supported by the Bloomberg American Health Initiative at the Johns Hopkins Bloomberg School of Public Health.