In 1956, the Federal Aid Highway Act initiated the development of the US interstate system — which would span 43,000 miles to connect major US cities. While the effort was lauded at the time as a major public works accomplishment, the highway planning process has since drawn criticism for its impacts on communities of color and low-income neighborhoods. As researchers have become increasingly attentive to the ways in which federal policies have contributed to racial inequality - and as the body of evidence grows on the role place plays in shaping economic opportunity - economists have identified highway systems as an important area of study. Charoo Anand, a PhD student in Berkeley’s Economics department, is contributing to this literature with an examination on the impacts of the interstate system across the South.
Anand was inspired to study the US interstate system after moving to the Bay Area and noticing how transit networks differed from London, where she had completed her undergraduate degree at the London School of Economics. “It’s been such an adjustment for me. Between the tube and the bus, I feel like you can get anywhere in London.” By contrast, in the Bay Area, Anand noticed that most people rely on cars for transportation and that the freeway system created physical limitations to mobility in Oakland. As she was moving to the Bay Area to pursue a PhD in Economics, she viewed these limitations through an economic lens, saying, “Economists care a lot about incentives, and how that affects markets. And one thing that really changes incentives is, is it easy for me to get somewhere or not?”
Construction of the Century Freeway in Los Angeles, California. Like many places in the US South, interstate construction in the city fundamentally and permanently altered the geography of communities of color, historians describe.
In her project, Anand is looking at how interstate construction affected segregation and inequality in the US South. She does this by using Census data to compare income and demographic outcomes for counties that the interstate system passes through to outcomes for counties that did not receive an interstate, but might have. Construction of the interstate system was done through a centralized process involving engineers, who had clear design objectives for where interstate highways were placed. The documentation of these objectives made it possible for Anand to map out counterfactual arrangements that could have been created, but were not. To give each county a score that corresponds to their likelihood of receiving an interstate, Anand simulated many alternative layouts for the US interstate system. For each county, she counted how many times it was included in a simulated layout, so counties appearing in more hypothetical layouts received higher scores. The scores that Charoo assigns allow her to control for factors other than interstate development when comparing county-level outcomes for income and segregation, restricting any variation to only that caused by the presence of interstates.
Anand found that counties that received an interstate remained more segregated for decades than they would have in a counterfactual scenario. She also found that poverty rates among white individuals were lower in counties that received interstates, as compared to those that did not – but that this was not true of Black people living in the same counties. These findings suggest that interstate construction had an anti-poverty effect for white people who lived nearby, but not Black people.
In the next stage of her project, Anand is continuing to study the unintended distributional impacts of interstate construction, with the advent of new econometric methods and data. In particular, she has discovered from archival planning documents that cities with populations over 50,000 in 1940 were more likely to be included in the interstate system. Anand will leverage this non-random exposure to build stronger empirical evidence for her findings.
Anand’s results suggest that policymakers should be especially diligent about considering potential consequences when making investments in infrastructure projects. She notes that infrastructure projects require particular care because they cannot easily be undone: “The highway system was mostly decided in the fifties. There've been some additions, but we're pretty much set with it now,” she described. As the federal government seeks to make major investments in infrastructure, Anand notes that racial and economic equity considerations should play a more central role in the planning process. “There have been calls to have racial impact evaluations…like how we have environmental reviews of infrastructure projects, and of housing projects. And those committees need a set of tools for measuring how projects affect segregation and inequality.”