In the tenth episode of “That Wikipedia List“, Sam of Wendoverpro used archival footage to talk about the history of right side-driving, what countries use right-side driving and what happened on Dagen H, the day in which Sweden switched from right-side driving to left-side driving.
In 1955 Sweden held a referendum on the issue of driving directionality and a staggering 83% voted against changing the direction. The national legislature known as the Riksdag promptly responded by deciding to make the change. The rational was that every single one of Sweden’s neighbors drove on the right and most imported cars—which were the cheapest cars—were designed to be driven on the right. In the months leading up to Dagen H every intersection was outfitted with an extra set of signals and signs wrapped in black plastic. 8,000 busses were retrofitted with new doors on the right side and the rest were sold to Pakistan and Kenya. New lines were painted on the roads then covered in black tape. Milk cartons and underwear with the day’s logo were sold in stores around the country. Contests were held for songs about the change. Then finally, on September 3rd, 1967 at 3pm, the law switched, and the entire country had one enormous traffic jam as drivers slowly inched across the white line to get to the new normal. No one died that day on Swedish roads… in fact, nobody died the day after as well.