Trends in Auto Access

The most notorious and instructive example of transportation infrastructure as land use change in the US involves interstate freeway segments used to destroy particular communities in order to provide access to others. From Houston to St. Louis to Minneapolis, from Rochester, NY to Portland, OR, freeway construction projects were planned to bisect, disrupt, and simply replace neighborhoods inhabited by the poor, racial minorities, and other disfavored groups. These freeways were not built to accommodate existing travel demand. Instead, they served the dual purpose of land use change: through the primary mechanism of destruction of unwanted neighborhoods, and the secondary mechanism of providing accessibility to the remaining urban core to new areas of land development. In other words, the supply of urban freeways supply increased accessibility from suburban origins, created changes in suburban land use at the origins of that new accessibility, and thus induced demand for travel. The negative feedbacks on accessibility eventually occurred, generating political pressure to continue freeway expansion and shore up accessibility. In places like Minneapolis-St. Paul, the freeway infrastructure investments have continued, leading to nearly uniform job accessibility across the region in both urban and suburban areas, for those can and are able to afford to drive a car (Figure 3.1).

Through the end of the previous decade, the job accessibility by auto changed little across most urban areas, and reflected stability in both the travel time and job destinations in this period. Figure 3.2 depicts the time series of job accessibility in the top 50 urban areas of the US. Each line represents the average number of jobs the typical resident of the area could reach, driving for 30 minutes from their residential origin block.

In spring 2020, the worldwide COVID-19 pandemic arrived in the US. The policy response differed across the country, but whether formal lockdowns were introduced or not, daily travel was significantly disrupted, especially for higher-income workers who were able to transition quickly to working from home. Because this same demographic typically commutes by car, congestion vanished and observed roadway speeds approached free-flow throughout the day in many urban areas. Because the NAE uses observed roadway speeds to calculate travel times from each block to all possible job destinations, the average observed job accessibility by auto spiked significantly (Figure 3.2; travel year 2020 reflected speeds observed the year prior to June 2020, and thus mostly pre-COVID conditions). 

In 2021, the jobs reachable in an auto commute were universally higher, and mostly much higher. There is a surface irony in that the disappearance of trip making by auto was the main determinant of this increased auto access; essentially the suppression of the feedback cycle in Figure 1.3 by outside forces. But the feedback cycle did return, and by 2023 the easy access to destinations available to drivers had shrunk back toward pre-COVID levels. But not all the way, and not everywhere.