September 3, 1967.

After forty years of voting down attempts to switch traffic from left-hand to the right, Sweden's Riksdag approves the change for driving to be done on the right-hand side of roads. Neighboring countries like Finland and Norway are already driving on the right, and Sweden has seen an increase in passing collisions due to left-hand drive cars combined with left-hand driving.

After four years of preparation, training and an awareness campaign (see logo), H-Day arrives. Officially known as Högertrafikomläggningen (The right-hand traffic diversion), it marks the transition from the old days to the new. Streets and intersections have been canvassed and given new markings, signs & lights. Traffic restrictions are implemented in metro areas. Vehicles have been modified, from transit buses and their stops all the way down to cars being fitted with new headlamps for right-hand driving. 

With all the precautions in place, the transition taking place this Sunday morning should go smoothly. For the most part it does, but as these photos from Stockholm show, there are always exceptions.