3 September 1967: Sweden switches to driving on right-hand side of the road

This day in Sweden in 1967 was known as Hgertrafikomlggningen –  the “right-hand traffic diversion”. Also called Dagen-H, it was the day the country switched from driving on the left side of the road to driving on the right.

While the rest of mainland Europe had settled on driving on the right hand side of the road, Sweden decided it preferred the left. This caused problems. People had to switch from left to right at the borders with Norway and Finland, plus – oddly – virtually every car in Sweden at the time was left-hand drive. Nevertheless, Swedes seemed to like it that way.

The government first proposed changing over to the right as early as 1920, but was met with stiff resistance. But it kept on debating it every year. In 1955, it held a referendum – 83% of the population said they'd rather stick on the left, thanks.

But after a while, the government thought they'd just get on and do it. So in 1963, the switch was approved, and the Statens Hgertrafikkommission was set up to administer the change. A huge PR campaign was set up to get Swedes used to the idea. Junctions were redesigned, and 360,000 new signs put up in preparation.

And so, at 4:50 AM on Sunday 3 September 1967, all traffic was ordered to come to a standstill for ten minutes. Then, at 5:00 AM, everyone switched sides.

Boringly, chaos did not ensue. This was Sweden, after all. Everyone behaved themselves, and the accident rate fell. Insurance claims dropped by 40%, only returning to their previous levels after two years.

Sweden isn't the only country to change sides, of course. Iceland followed suit in 1968, and a whole host of former British colonies in West Africa did it in the 1970s. But it's not all one-way traffic. Samoa switched from right to left in 2009.