An important article by Mark R. Stevens in the January 2017 issue of the Journal of the American Planning Association1 suggests that an increase in population density leads only to a modest decrease in automobile use. The article is based on meta-regression analysis, a technique familiar in medical research that has the great advantage of increasing validity by merging the results of numerous case studies.
The author finds that there is some relationship between density and automobile usage, but that the “elasticity” is only between .22 and .10. That is, a 1% increase in density would reduce driving between .1 and .22%. This is an incredibly important finding, since densification of American cities has often been proposed as a way to decrease automobile usage.
The article comes with several critiques from other scholars2. Some point out that an elasticity of .22 is not so low. Others criticize various aspects of the study. I’m particularly inclined to agree with the criticism of Ewing and Cervero that the meta-regression technique is flawed in this case by the inclusion of several studies of foreign cities, including several Third World cities. In Mexico City, for example, many well-off people live in close-to-center-city high-density neighborhoods—and are far more likely to own, and use, automobiles than the relatively poor people who tend to live in lower-density, often informal developments at the edge of the city. It’s not clear that instances like this are particularly relevant to understanding the relationship of density and driving in cities in the United States and elsewhere in the developed world. Still, cases like this do not really undermine Mark R. Stevens’ basic finding that the correlation between increasing density and reduced automobile usage is not spectacularly high.
I spent last weekend in Los Angeles, and I was particularly reminded of this article when I passed through the stretch of Westwood along Wilshire Boulevard just east of Glendon Avenue. I have no special knowledge of this area, but I’ve visited it many times and have always been struck by the near absence of anyone walking on the streets despite the presence here of numerous 25-or-so-story apartment buildings. There may be no urban residential district in the United States with bigger buildings and fewer pedestrians. Here’s a photo:
The lack of pedestrians is in many ways somewhat surprising, and not only because of the area’s density. The Westwood Wilshire corridor is close to UCLA; there are many stores and quite a number of pedestrians in nearby Westwood Village; and the area has excellent transit: Wilshire Boulevard has some of the most frequent bus service in the United States3. But you sure don’t see many pedestrians on Wilshire Boulevard, with the partial exception of a tiny number of people on their way to or waiting at bus stops. And, well, it’s hard not to seem a bit racist in talking about this, but the fact that most of the people you see at bus stops or walking look Hispanic suggests that they aren’t the people who live in the apartment buildings; the area is less than 2% Hispanic. Presumably many of these people work in the buildings in one capacity or another. I’ll admit that the river of traffic on Wilshire Boulevard is a deterrent. It’s not very pleasant walking there (although I suspect that most pedestrians would hardly notice if they had some company). There aren’t any stores on this stretch of Wilshire either. But, still, you’d expect a high-density residential area to be a little more, well, “vibrant.”
All this led me to look up census data for this area when I got back home. There are some difficulties with interpreting census data in this district, because there are small apartment buildings and single-family houses behind the wall of tall apartment buildings on Wilshire, and the tract and even the block-group and block boundaries inevitably cover areas of both high-density and medium-density housing. None of the census numbers apply to the apartment buildings only. But they still tell you something. In 2010, there were 6457 people living on the first six or seven blocks of Wilshire Boulevard east of Glendon Avenue4. The population density of these blocks was 16,150 people per square kilometer (41,828 per square mile), which is pretty high. Here’s a map:
For anything other than rudimentary population figures, you must look at American Community Survey data at the tract or block-group level. In the three tracts that cover the bulk of the area5, 74.6% of the working-age population drove to work and only 1.2% took transit in 2008/2012. Here’s a map:
In other words, the Westwood Wilshire corridor, despite its density, is extraordinarily automobile-oriented.
I also looked at some other census numbers. The corridor is a well-off, cosmopolitan area. Per capita income in 2007/2011 was high at $83,274. There are a fairly large number of older people (23.2% 65 and over) and few children (10.9% less than 18). 32.2% of the population was born outside the United States. The ancestry of the population is 11.2% Iranian and 8.6% Russian; it’s very likely that most of the people with Russian ancestry are Jewish. Tracts with somewhat similar characteristics (although with many fewer Iranians) in New York (parts of Forest Hills, say) or Chicago (along Lakeview Avenue in Lincoln Park, for example) would have many more pedestrians and a much larger transit share.
When I’ve asked local people to account for the absence of pedestrians in this area, I’ve gotten an answer along the lines of “Nobody walks in LA,” and, when I’ve asked about the low transit use, the response has mostly been a grimace. An ethnographer must be a little skeptical of the responses (s)he receives, but, while there is no way to be certain, perhaps in this case one should trust the answer. In Los Angeles doing errands on foot and bus riding are associated with poor people, and many middle-class people with a choice will not do errands on foot or ride buses6. Cultural prejudices matter7. There is also of course the fact that, in an urban area with a weak downtown like Los Angeles, transit just isn’t as useful for as many work journeys as it is in cities with a stronger center8.
It must be added that, despite the stereotype, there are plenty of places in Los Angeles with a substantial number of pedestrians, including quite a number largely frequented by members of the middle-class, for example, the walkway along the beaches in Santa Monica and Venice; central Santa Monica; the Melrose District; and perhaps central Hollywood and (increasingly) parts of Downtown. There are also areas where poorer people congregate, notably Broadway downtown. Of course, it’s significant that pedestrians’ goals in most of these areas are often recreational. You don’t see many people who are, say, carrying groceries home on the Third Street Promenade.
Data from the Westwood Wilshire corridor, in other words, support Mark R. Stevens’ argument in the article cited above that the relationship between high density and low automobile use isn’t as substantial as one might imagine it would be. One possible lesson to draw is that changing the culture of places like the Wilshire corridor would be more effective in reducing driving than building infill. Of course, this isn’t something that can be engineered by government action.
It’s an interesting and important question whether the arrival of Metrorail to Westwood in something like 2024 will lead to more transit usage and more pedestrians. It might. I lived in Washington, D.C., as the Metro Red Line was being extended into the northwest sector of the city. After stations opened, many more people could be seen walking in the streets. Presumably automobile use declined during this period. Since rail transit is usually not quite as stigmatized as—and is also faster than—bus transit, it’s perfectly logical that adding rail in areas of high density would have some effect.
But new subway lines are far and few between. There are plenty of urban neighborhoods in the United States with fairly high densities where only a change in culture would seem able to reduce automobile use.
- Mark R. Stevens, “Does compact development make people drive less?” Journal of the American Planning Association, 83:1, pages 7-18. ↩
- See previous footnote, pages 19-28, especially Reid Ewing and Robert Cervero, “Does compact development make people drive less? The answer is yes,” Journal of the American Planning Association, 83:1, pages 19-25. ↩
- The 720 express, according to the printed timetable, runs as often as every 2 minutes during rush hour and every 8 minutes at midday. There are also local buses. ↩
- That is, the first six blocks on the north side of Wilshire and the first seven on the south side. ↩
- Tracts 2652.01, 2652.02, 2656.01. These tracts cover the Wilshire corridor as well as several adjoining blocks. The three tracts had 9261 people in 2008/2012 and a population density of 6860 per square kilometer. I am pretty sure that most of the population in these tracts lives in apartment buildings on Wilshire. ↩
- In the 5-county Los Angeles metropolitan area, there’s a highly significant negative correlation (-.332) at the tract level between the percentage of workers 16 and over who use public transit to get to work use and per capita income; that is, higher income is strongly associated with lower transit use. In the Chicago metropolitan area, there’s a (not very significant) positive correlation (+.057) between these two variables. ↩
- So, probably, does the proximity of UCLA. 16.0% of the working-age population in the three tracts reported that they walk to work. They’re not very visible, however. Perhaps they quite reasonably avoid Wilshire. ↩
- Here’s a related factor. Despite the frequency of bus service, it isn’t very fast. It takes nearly an hour even on the 720 to travel the 18 kilometers (11.2 miles) between Westwood and downtown Los Angeles. There aren’t that many stops, but there are dozens of red lights and a huge amount of traffic to contend with. ↩