Dagen H

Dagen H, ("H day", wherein H stands for the Swedish högertrafikomläggningen, "the right-hand traffic diversion"), was the day on which Sweden switched from left-hand traffic to driving on the right. It was by far the largest logistical event in Sweden's history.

The switch was scheduled for 3 September 1967, at 05:00. All non-essential traffic was banned for 4 hours before this point, which were used to reconfigure traffic signs, reconstruct bus stops. All remaining traffic had to come to a halt by 4:50, carefully change to the right side of the road, and was then allowed to continue at 05:00.

Special gloves where handed out, the left one of them painted in a deep red, to remind drivers to stay on the correct side. Special, hexagonal yellow-and-blue signs with an "H" were put up everywhere for the same reason.

Why did Sweden decide for the change in the first place? All of its neighbors had right-hand side traffic, including Norway and Finland, which complicated crossing the borders. Also, most Swedes had cars with the steering wheel at the left, which led to many accidents in small passageways. However, the change was widely unpopular, in a referendum prior to the change 83 percent voted against driving on the right.

Iceland switched to driving on the right in 1986.