As planners race to reconceive streets and sidewalks toward more environmentally or socially productive ends, the widths of those rights-of-way are often ignored, though it’s clear to many observers that they are too wide for their purposes. In “The Width and Value of Residential Streets” in the Journal of the American Planning Association (Vol. 88, No. 1), Adam Millard-Ball aims to not only quantify the proportion of American cities devoted to automobile circulation, but estimate the value of that land and its opportunity cost from an economic perspective. Instead of mandating width minimums, as is currently common, Millard-Ball proposes relaxing standards to allow developers to determine appropriate street widths.

Millard-Ball notes that U.S. cities, in contrast to their international counterparts, dedicate a relatively greater proportion of land area to streets and explains how federal and municipal regulations have historically overprescribed street size. A typical street in modern Osaka or Paris is under 20 feet wide, while many American cities require widths of between 50 and 60 feet.

But how can we approach the problem of defining the value of streets? What functions do they serve and what functions do their presence or dominance foreclose (i.e., their opportunity cost)? Millard-Ball cycles through several functions performed by streets, emphasizing how each can still be achieved with narrower streets: Access value, including for utility and emergency vehicles, can still be maintained with widths as small as 16 feet, while movement and storage values (of automobiles, mostly) are being diminished in recent years in any case, due to reasonable alternatives to on-street parking and the broad goal to calm or reduce traffic.

In the article’s empirical section, Millard-Ball analyzes the widths and values of streets in a 20–county sample. He finds an average width of 55.2 feet and a substantial portion (41 percent) of street widths sized at exactly 50 or 60 feet, likely owing to municipal ordinances. For the values of those streets, Millard-Ball uses data on standardized land values by census tract, finding coastal Californian streets to be the priciest and streets in counties in Texas and Tennessee on the lower end. The total land value of streets in Los Angeles, for example, approaches $500 billion.

While the author seems to hone in on 16 feet as an appropriate width, pointing to international examples that successfully balance street functions within this parameter, he concludes that it’s most cost– and space–effective to leave this decision up to developers, instead of overly expansive municipal ordinances: “Developers are likely to be in the best position to optimize the allocation of land between streets and housing.”

How would we adjust our built environment in light of the article’s findings? While Millard-Ball concedes the logistical problems associated with realizing cities’ underutilized land value, the findings are a testament to how historical zoning and car-centric development patterns have produced a host of problems, particularly spatially inefficient cities. Though developers are not usually understood as the antidote to urban America’s ills, Millard-Ball’s characterization of developers as reasonable, informed allocators of land uses and keen responders to residential and economic demands was convincing — if not another reminder of the past misjudgements and current shortcomings of land use planning.

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