On Sept. 3, 1967, every car in Sweden came to a stop at 4:50 a.m., carefully switched from the left side of the road to the right, and proceeded at 5 a.m.
At 4:50 a.m. on September 3, 1967, as crowds of people gathered to watch, all vehicles on the road were instructed to come to a halt. They were then directed to move carefully from the left side of the road to the right, and wait. At the stroke of 5:00, following a radio countdown, an announcement was made — “Sweden now has right-hand driving” — and traffic was allowed to resume.
The whole nation switched to right-hand traffic overnight. And to the planners’ immense credit, no fatal accidents were associated with the change, and accident rates went down in the year that followed.
A non-binding referendum on the introduction of right hand traffic was held in Sweden on 16 October 1955.
Dagen H – Högertrafikomläggningen
The voter turnout was 53.2%, and the suggestion failed by 15.5% against 82.9%. However, eight years later, in 1963, the Riksdag approved the change. The traffic in Sweden switched from driving on the left-hand side of the road to the right on 3 September 1967 (see Dagen H, Swedish for H Day)? H stands for Högertrafikomläggningen.