Dagen H

Dagen H, also known as Högertrafikomläggningen (the Right-hand Traffic Conversion), was the day on September 3, 1967, when Sweden switched from driving on the left-hand side of the road to the right-hand side. The "H" in Dagen H stands for "Högertrafik," which translates to "Right-hand traffic."

Prior to 1967, Sweden was one of the few remaining European countries with left-hand traffic. This caused problems, particularly at border crossings with neighboring countries that drove on the right, and also contributed to head-on collisions. Many Swedes also drove left-hand drive vehicles, making overtaking particularly dangerous.

The decision to switch was made after a referendum in 1955 where a large majority voted against the change. Despite the referendum result, the government eventually passed legislation to make the switch, arguing it was necessary for safety and international harmonization.

A comprehensive information campaign was launched in the years leading up to Dagen H to prepare the public. This included posters, television and radio broadcasts, and even specially designed merchandise. On Dagen H, at 04:50 local time, all non-essential traffic was prohibited. Between 04:50 and 05:00, all vehicles had to stop and carefully move to the right-hand side of the road. At 05:00, traffic resumed on the right. Special temporary lane markings were used to guide drivers, and speed limits were reduced in the immediate aftermath to allow drivers to adjust.

The conversion was a major logistical undertaking, requiring the redesign of road signs, bus stops, and other infrastructure. Despite initial concerns, the transition was largely successful and led to a significant decrease in traffic accidents in the short term.