How do you quantify the cost of sprawl? There are so many, after all. For local governments, the cost of single-family homes and shopping malls tend to outweigh the tax benefits. Sprawl drives up fuel and energy consumption, commute times, and per capita land use, and drives down individual health, physical activity, and even psychological well-being. A 2015 report by LSE Cities and the Victoria Transport Policy Institute bundled together a number of those outcomes, and estimated in very broad strokes that sprawl costs the U.S. close to $1 trillion every year. 

Now, Daniel Hertz of City Observatory has come up with a more targeted approach to index the price of spread-out development, in time and money, for American workers.

Combining the the 50 largest metro areas in the U.S., he found, commuters pay more than $107 billion annually, which is about $1,400 per commuter, on average. Those are the dollar costs of the number of additional hours Americans spend traveling to and from work due to sprawling land-use patterns—which, by their methodology, ends up being around 3.9 billion extra hours total, or 50 hours per worker, per year.

To get to those rather staggering numbers, Hertz developed a unique methodology: He took the average commute length, in miles, for America's 50 largest metros (as determined by the Brookings Institution), and looked at how much shorter those commutes would be if each metro were more compact. He did this by setting different commute benchmarks for clusters of comparably populated metros: six miles for areas with populations of 2.5 million or below, and 7.5 miles for those with more than 2.5 million people. These benchmarks were just below the commute length of the metro with the shortest average commute length in each category, but still 0.5 miles within the real average of the overall category.

He multiplied the difference between the benchmark and each metro's average commute length by an estimated cost-per-mile for a mid-sized sedan, then doubled that number to represent a daily roundtrip "sprawl tax" per worker, and then multiplied that by the number of workers within a metro region to get the area's daily "sprawl tax." After multiplying that by the annual number of workdays, and adding up each metro, he had a rough estimate of how much sprawl costs American commuters every year. 

Then Hertz calculated the time lost by all this excessive commuting, "applying average travel speed for each metropolitan area to its benchmark commute distance, as opposed to its actual commute distance," he explains in a blog post.

Hertz's "sprawl taxes" vary from metro to metro, as shown above. Atlanta commuters are paying the most out of anyone else in the country, wasting more than four full days in excess commute time each year. In New Orleans, workers lose only about seven hours a year. 

Hertz's methodology may not be perfect. It might have served his analysis to have grouped these metros into narrower buckets, or by average commute distance rather than population. While it's true that large cities tend to have longer commutes, there are exceptions. New Orleans and Louisville are non-dense, fairly sprawling cities, but their highways are built up enough that commute distances are fairly short. To really accurately assess the "sprawl tax" in cities like those, you'd have to include the other costs of spread-out development mentioned previously—the health impacts, the pollution, the car crashes, and so on. Hertz only addresses commute lengths and time. 

Still, analyses like this are sorely needed, especially considering how much time and effort has been dedicated to calculating the costs of traffic congestion. Americans may lose a lot of productivity, time, and money sitting in their cars, but attributing these losses to traffic isn't quite right. Congestion, in fact, is going down nationwide. But the distance between jobs and homes is getting wider, and in large part, that's because of sprawling land-use patterns.   

This is a national concern, writes Hertz's colleague, Joe Cortright, who also looked at how America stacks up against its international peers when it comes to these costs. He didn't do a full analysis of sprawl in metro areas in other countries, but instead looked at how much of their household budgets the citizens of 15 European countries and Canada spend on transportation. Again, no surprises there: The U.S. spends about $1,500 more per household on transportation costs and about $770 more per worker on commute-time costs than do these other high-income nations.

While there are a number of factors at play here, land-use patterns are a central driver of this cost disparity, Cortright argues. Sprawl is "dragging down our disposable income and free time relative to residents of other countries," he writes. Urban economists, please keep crunching numbers on how much sprawl is costing Americans. The best numbers may actually drive planners to take some action.