Support for legalizing recreational marijuana has been steadily growing for decades. Last November, California, Nevada, Massachusetts and Maine voted to legalize recreational marijuana for people age 21 or older. Leading up to the election, voters were inundated with arguments from both sides of the debate. One of the most convincing argument against legalization was the risk for increased traffic accidents and fatalities. The graph on the left shows traffic fatality rates in the only two states with multiple years of legal recreational marijuana, Colorado and Washington, versus surrounding states. Although Colorado and Washington had about 30% lower rates of traffic fatalities in general, since legalization their fatality rates have increased 2.7x more quickly than surrounding states. This means that if these trends hold, by 2023 the rates will converge. In terms of an apocryphal tortoise and hare race across a football field, this would be like starting the tortoise at the 63-yard line, but the hare is going 6.9 miles per hour to the tortoise’s 2.6. So please remember not to drive under the influence of any drug including marijuana (and especially alcohol).
Data on the Rocks 