"Dagen H," or "The Day of H," refers to the day on September 30, 1967, when Sweden officially switched from driving on the left side of the road to the right. This significant change aimed to improve road safety and align with neighboring countries that already drove on the right. The transition was carefully planned and involved extensive public information campaigns. On Dagen H, traffic signs were changed, and drivers were instructed to adapt to the new rules. The switch was executed smoothly, with minimal accidents reported on the first day. This event is often cited as a successful example of a nationwide traffic reform.