Which are the fastest and slowest (car-wise) U.S. metropolitan areas? The task of comparing speed across U.S. cities is daunting: First, data on car trips is sparse. Second, just ranking cities by the average speed (in km/h or miles per h) of trips is not a good way to spot the fastest and slowest U.S. cities. Indeed, in the fastest cities, households tend to use their car more! Hence just comparing the average speed of a trip in, say, Miami, FL with the average speed in Grand Rapids would likely overestimate the speed difference between those two cities.
Victor Couture, Gilles Duranton, and Matthew Turner solve these two issues. First, they use two large surveys of household trips — such data includes the trip’s purpose, its duration, and its length. And second, they estimate the demand for car trips as well as the supply. In their paper, the authors build a metropolitan area speed index. Miami is the slowest city, while no other city than Grand Rapids (!) is the fastest city in the United States.