The unexpected effects of daylight-saving time: Traffic accidents in Mexican municipalities

Objective: Several countries implement the DST policy for energy saving purposes. However, by artificially changing the distribution of daylight, this practice can have unforeseen effects. The objective of this work is to measure the impact of DST on road accidents in Mexico.Methodology: Using hourly data, two empirical strategies are used: regression discontinuity (RDD) and difference-in-differences (DD).Results: The main finding is that DST significantly reduces the total number of accidents in metropolitan areas. However, there are no clear effects on the number of fatal accidents.Limitations/Implications: DST is implemented regardless of demand conditions and the economic cycle. Seasonal changes in prices and production can be difficult to capture before and after the time change. We introduce variables that mitigate the (potential) identification problem.Originality: this is the only study measuring these effects in Mexico (and one of the few with data from emerging countries).Conclusions: The DST is currently being discussed in Mexico, and our study offers a more comprehensive evaluation of the policy, not only from the standpoint of energy efficiency.