Wikipedia
H-dagurinn or Hægri dagurinn ( Icelandic: Right day) on 26 May 1968 was the day that Iceland changed from left hand traffic to right hand traffic. The change itself occurred formally at 6:00 AM.
Iceland had already planned to switch to right-hand traffic in 1941, but it was interrupted by World War II and so it was postponed.
The country's parliament made the following demand of the government on 13 May 1964: "Alþingi urges the government to initiate as soon as possible research into how best to move the traffic to the right hand side of the road."
The Traffic Commission (Umferðarnefnd) was assigned to handle the task. Cost due to the change amounted to over 33 million kronur due to modification to buses and 12 million kronur due to changes to infrastructure. During the night before the change 1662 signs all over the country were changed, making the total of signs changed 5727.
The only injury from the changeover was a boy on a bicycle who broke his leg.
In accordance with risk homeostasis theory, traffic accident rates briefly dropped as drivers overcompensated for the increased risk from driving on the unfamiliar side of the road, before returning to the level predicted by the trend prior to the changeover.