Commuter Characteristics in US Cities

How do people who commute via public transit differ from those who drive? I’ve been thinking about this question for a while. Based on what I’ve read, the prevailing wisdom today seems to point to widespread demographic differences between public transit commuters and car commuters. There is strong evidence suggesting economic and racial disparities between the two groups. I’ll talk about why one might expect each of those disparities, and then dig into the data to see how widespread these differences might be.

There are clear cost advantages to mass transit that produce an economic disparity between transit and car commuters. According to AAA, owning a car in 2017 cost an average of $8,849 per year (nationally, and this doesn’t take into account parking costs in large cities), whereas an MBTA pass in Boston was $84.50, or $1,014 annually. Given this reality, it makes sense that transit riders would be more economically disadvantaged than car commuters, and that this difference would manifest in any number of other markers: lower homeownership rates, more debt, higher poverty rates, less household wealth.

In addition to an economic disparity between different kinds of commuters, one might also expect a racial disparity. The data seems to confirm this. A report from the American Public Transportation Association, Who Rides Public Transportation, found that 24% of transit riders are African American; in comparison, African Americans make up 12% of the general population.

Why might transit use be tied to race? The story is not as simple as race being associated with income, and income being associated with mode of transit. Rather, generations of government policies throughout the 20th century reinforced racial segregation in urban areas, which in turn contributed to de facto segregation of mass transit. Douglas Rae’s book, Urbanism and its End, describes how New Deal policies singled out minority neighborhoods. In the 1930s, the Federal Housing Administration and Home Owner’s Loan Corporation began publishing “Residential Security Maps” that were designed to downgrade the ratings of nonwhite neighborhoods. This reduced home values in those neighborhoods and made it difficult for nonwhite residents to secure home loans (Rae, Chapter 8, “Race, Place, and the Emergence of Spatial Hierarchy”). Post WWII, federally-subsidized suburban development enabled white city residents to move to newly constructed suburban neighborhoods financed through the GI Bill. Private sector discrimination denied nonwhite residents that same opportunity, deepening the racial and economic divide between cities and suburbs. As cities became increasingly nonwhite in the latter half of the 20th century, there was opposition at all levels of government to investing in urban infrastructure and funding public transit. To learn more about this history, I recommend an article from StreetsBlogUSA, “How Racial Discrimination Shaped Atlanta’s Transportation Mess.”

Clearly, there is evidence to suggest deep economic and racial disparities between different kinds of commuters. I’m interested in understanding how those disparities look across cities. To do that, I compared income, poverty rates, homeownership rates, race, and citizenship status.

To limit the scope of this analysis to large cities, I chose the 100 US cities that had the largest total number of car and public transit commuters, as measured by the 2017 American Community Survey. The following five graphs show different demographic variables, for each city, for car commuters and public transit commuters. Each set of boxplots allows the reader to filter the values by city or state.

For each of the five variables I looked at, the demographic difference between car and public transit commuters was statistically significant and conformed to the expectation that public transit users are relatively economically disadvantaged and more likely to be African American or a citizen of another country.

However, the above box plots and maps also demonstrate the substantial variability and diversity among large US cities. There are many cities on the list where the disparity between car commuters and transit commuters is quite large. In other cities, particularly those in the Northeast and West Coast, the size of the disparity between car commuters and public transit commuters is very small. There are also a handful of cities that do not conform to expectations. In these cities, car commuters actually had lower earnings, higher poverty rates, etc. than public transit commuters.

There are several possible explanations for why this is, and the one I want to emphasize is that the quality of public transit varies substantially across the country. Historical development patterns as well as contemporary practices have how accessible and attractive public transit is to commuters in different cities. In much of this country, public transit is a mess. Many cities on my top 100 list still don’t have light rail in 2019. (If you want to see what decades of disinvestment and political resistance do to mass transit in a city, read about it in the Tampa Bay Times.)

In contrast to the vast majority of American cities, a few have adequate or even preferable public transit. For example, Boston became the first city in the US to have an operational streetcar, as reported by the Boston Globe, in 1897. And today, it joins San Francisco, New York, and Washington, as home to one of the best public transit systems in the country. In those cities and others, taking public transportation every day sometimes means being able to afford living in more expensive downtown neighborhoods that are transit-accessible. In a housing boom that prices residents out of cities and into their surrounding metro areas, daily public transit use is sometimes a privilege. However, looking at large cities across the country, those select few cities are the exception, not the rule.

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Data sources: United States Census Bureau

Programs used: MS Excel, Tableau