In the U.S., the number of suburban jobs has grown in recent decades, extending the broader suburbanization trend that took root in the 1950s, and many cities have become sprawling metropolises that put significant distance between homes and workplaces, resulting in longer commutes. But do some racial groups bear disproportionately longer commutes than others? If so, how is this inequality explained?

In their paper, "The Problem Has Existed Over Endless Years: Racialized Difference in Commuting, 1980–2019," devin michelle bunten, Ellen X. Fu, Lyndsey Rolheiser, and the Philadelphia Fed's Christopher Severen attempt to answer this question by investigating whether commuting outcomes in the U.S. are equitable by race. They calculate differences in travel times for White and Black commuters, and they identify the principal factors that account for these differences. They interpret the inequality of travel times as a racialized difference — that is, as a byproduct of an entrenched process that involves race.

Prior research focused on a small group of select cities, but these economists wanted a nationally representative analysis, so they used census data on commuting trips within all major commuting zones across the U.S. Their study's time frame is likewise broader than what has been examined in the literature, covering the period between 1980 and 2019. (Much of the preexisting literature focuses on the 1970s and 1980s.)

The authors set the scene by using historical data to establish a few baseline relationships. For instance, they show that on average, differences between Black and White commuting times shrank between 1980 and 1990. After 1990, even though average commute times trended upward for both groups of workers, there was additional convergence, if at a slower pace than during the prior decade. Despite this overarching tendency toward convergence, commute times continued to be longer for Black workers, and this disparity persisted through 2019. The authors then set out to explain why.

They find that commuting times depend on many factors that can affect how two racial groups experience their daily journeys. Mode of transportation, location of residence, type of employment, and type of commuting zone (small town versus big city, for instance) are among the factors they account for.

The authors show that mode of transportation (car versus bus, for example) is a particularly influential factor behind differences in commute times, and they identify several surprising outcomes when they deepen their inquiry into this one factor. They reveal, for example, that Black commuters who drive to work face longer commutes than White drivers even when both groups have similar demographic characteristics (such as income levels and educational attainment). To be sure, this difference in driving times has become decidedly smaller over time (indeed it has virtually disappeared outside of big cities); but a persistent difference within urban environments suggests that "patterns in residential and workplace locations lead to longer commutes for Black workers." These patterns, the authors contend, reflect an embedded race-based marginalization by which Black drivers are likely to live farther away from their jobs than White workers.

Other commuting modes, such as subways, show similarly eye-opening results. Even though subways operate in only a few U.S. cities (and thus produce a smaller data sample than car-based commuting), the difference between Black and White commuting times via subways is significant and has actually grown wider during the period studied.

The results hold, the economists find, even when they adjust their model to focus on relatively small geographic areas (such as individual census tracts). When looking through this narrower lens, the authors find additional evidence of persistent racialized differences in commuting times within large, transit-dependent cities. These differences are rendered even more obvious when compared to differences in commute times in smaller cities, where White and Black travel times generally show more convergence. This persistent difference in big-city commuting times, the authors note, likely reflects the residential patterns in which Black workers have longer commutes from their employers than White workers do.

Throughout their work, the authors employ a conceptual framework that bundles commuting characteristics under the rubric of spatial stratification (which they define as "the organization of a city whereby segregated Black neighborhoods feature higher travel costs to jobs than do segregated White neighborhoods"). With this framework in mind, they test whether more-stratified cities show a more-persistent difference between White and Black commuting times.

Their results suggest that spatial stratification indeed contributes to racialized differences in commute times. In cities where residential segregation is declining, for example, the racialized difference tends to decline; Black commuters in these cities tend to live in zip codes that are closer to job-abundant areas, and their commutes are therefore more comparable to White commutes. In another notable insight, their findings dispel the notion that sprawling cities have more racialized commuting patterns. Cities with a dense, prominent epicenter (like Chicago) and those with dispersed hubs of concentration (like Dallas) are equally capable of producing large, racialized differences in commuting times; both types of cities can have economic characteristics that enable residential segregation. One especially notable characteristic that explains these differences is the preponderance of higher housing prices in job-accessible neighborhoods, which is shown to increase the likelihood that Black residents will face longer commute times than White residents. These findings make sense when viewed through the prism of spatial stratification, because they show evidence of expensive housing markets resulting in longer travel times for a distinct segment of commuters.

Taken together, the explanatory factors identified in "The Problem Has Existed Over Endless Years: Racialized Difference in Commuting, 1980–2019" influence the difference between Black and White commuting times. The authors reveal that this difference, despite shrinking in earlier decades, remains significant, and their study explains the mechanisms that appear to drive this persistence.