The Driving Flip

On September 3rd, 1967, Sweden did something almost unimaginable: the entire country switched from driving on the left side of the road to the right — in a single night. This event, known as Dagen H (short for Högertrafikomläggningen, meaning “the right-hand traffic diversion”), was one of the most ambitious peacetime traffic operations in history. And somehow, it worked.

Before the switch, Sweden was one of the few European countries where people drove on the left. However, this created problems — especially since all its neighbors (Norway, Finland, Denmark) drove on the right. Cross-border travel was dangerous, and most of the cars in Sweden were already built for right-hand driving, meaning Swedes were driving on the left side with cars designed for the opposite — a recipe for head-on collisions.

So the government planned meticulously for years. In the early morning hours of Dagen H, at exactly 4:50 a.m., all traffic was ordered to stop for 10 minutes. During that pause, drivers carefully shifted to the right side of the road — and stayed there. Road signs, traffic signals, intersections, and bus stops had all been changed in advance. Even though people feared chaos, the switch actually resulted in fewer accidents in the short term, likely because drivers were extra cautious in the days that followed.

Dagen H remains a powerful example of how a society can coordinate massive change when people are informed, involved, and united. It’s also a reminder that traffic rules — which feel so natural — are actually deeply cultural agreements that can shift with enough planning.