Researchers at Stanford University and the University of Toronto figured this out from National Highway Traffic Safety Administration crash statistics for every presidential E-day from 1976 (Jimmy Carter) through 2004 (George W.). And compared the stats for the Tuesdays preceding and following each election.
The Election Day effect strikes Republicans and Democrats, car riders and pedestrians, men and women evenly — and without regard to the outcome of the election itself. It has a bigger impact on traffic deaths than Super Bowl Sunday.
But why? The scientists offer no helpful answer.
One explanation is increased traffic, but other factors might contribute. A 4% increase in average speed, for example, could yield an 18% increase in deaths even with no increase in average travel distance. Additional factors might include distraction (driver inattention), rerouting (unfamiliar pathways) enforcement (decreased police presence), and demographics (mobilizing unfit drivers).