On September 3, 1967, Sweden pulled off one of the most dramatic shifts in the history of road travel. Known as Dagen H—or "H Day," with the "H" representing Högertrafik (right-hand traffic)—this was the moment an entire nation moved from driving on the left to driving on the right. What might sound like a simple flip was anything but: it demanded years of groundwork, massive logistical coordination, and a sweeping campaign to win over the public.
Why the Change Was Needed
For years, Sweden stood out as an oddity on the European mainland. Neighboring countries like Norway and Finland had long embraced right-hand driving, yet Sweden stubbornly clung to the left side of the road. This mismatch created real headaches for cross-border travel, with millions of vehicles crossing between Sweden and adjacent nations annually. Making matters worse, more than 90% of Swedish drivers owned left-hand-drive cars—vehicles built with right-hand traffic in mind. The result? Overtaking on narrow roads was a nerve-wracking gamble, and head-on collisions were alarmingly common. Interestingly, when the public was asked in a 1955 referendum, a whopping 83% of Swedes voted against switching sides. Despite this opposition, Parliament pushed the change through in 1963, driven by surging car ownership and mounting worries over traffic safety.
Preparing for Dagen H
For four years, the Swedish Commission for the Introduction of Right-Hand Driving (HTK) orchestrated the country's transformation. Psychologists were brought in to advise on how best to retrain drivers' instincts, and a relentless wave of reminders flooded schools, media outlets, and advertising channels. To keep the switchover at the forefront of people's minds, the government distributed gloves, stickers, and other everyday items emblazoned with the iconic "H" logo.
As Dagen H drew closer, road crews worked feverishly to paint additional traffic lines and erect new signage—roughly 350,000 signs across the nation, with about 20,000 concentrated in Stockholm alone. Television programs hammered home the message, and even pop culture got involved: the earworm "Håll dig till höger, Svensson" ("Keep to the right, Svensson") became an unofficial anthem for the transition.
The Big Switch
Everything stopped at 4:50 a.m. on September 3. Every vehicle on Swedish roads came to a standstill as drivers carefully navigated over to the right-hand side and waited. At precisely 5:00 a.m., police gave the green light for traffic to start moving again. In larger urban centers such as Stockholm and Malmö, the changeover process had actually kicked off earlier so that work crews could reconfigure intersections in time.
Buses and public transit posed their own unique challenge.
Approximately 8,000 buses across the country needed retrofitting with doors on both sides, and over 1,000 brand-new buses equipped with right-hand doors were purchased. Meanwhile, certain cities—Gothenburg and Malmö among them—decided to scrap their tram systems entirely, swapping them out for bus routes rather than face the expense of reconfiguring the changing automotive updates.
Immediate Results
All things considered, the switchover was a striking success. Dagen H itself saw just 157 minor accidents reported nationwide, with 32 injuries and zero fatalities. In the grand scheme of things, experts credited the low accident count to two key factors: improved visibility during overtaking maneuvers in left-hand-drive vehicles and a sharp uptick in driver attentiveness. That said, accident rates gradually crept back to their pre-1967 levels within a few years. Still, Dagen H endures in collective memory as a testament to Sweden's capacity for adaptation—and a vivid illustration of the staggering complexity lurking behind what appears, on the surface, to be a simple change.