Rationing Can Backfire: The "Day without a Car" in Mexico City

Abstract

A ban restricting each car from on a specified weekday is found to have increased total in Mexico City. Because of the ban, cars effectively represent driving permits, and some households have bought an additional car and increased their driving. Greater use of old cars, congestion effects, and increased weekend may also have contributed to the disappointing results. The ban has high welfare costs and does not deliver the intended benefits of reduced driving—quite the contrary. The experience provides an interesting lesson in applied welfare economics. Theory indicates that this is a costly way of reducing traffic and pollution. But the finding that the strategy is counterproductive could be made only with applied quantitative analysis. In November 1989 the Mexico City administration imposed a regulation banning each car from a specific day of the week. Called Hoy no circula (this one does not circulate today), the Day without a Car regulation specifies that cars with license plate numbers ending with digits 0 or 1 do not drive on Monday, 2 or 3 do not drive on Tuesday, and so on. Restrictions do not apply on weekends. The regulation applies to all cars (except those of the fire department) and thus to firms as well as households. We use the term household for simplicity. Compliance is generally believed to be high: the police are visible and fines are heavy. The regulation has been both popular and controversial. Some people argue that it places a reasonable burden on car owners in order to alleviate congestion and pollution problems. Others argue that it is inefficient and unfair: inefficient in the way most rationing devices are inefficient; unfair because it is more easily avoided or accommodated by some than by others. Finally, some people are arguing that the regulation is counterproductive, actually increasing the levels of congestion and pollution because many households have purchased additional cars to circumvent the ban. This article analyzes the policy pragmatically. Section I shows how the results of rationing can be compared with those that would be obtained using market