Dagen H — Switch to Right-Hand Traffic 1967

On 3 September 1967, at 05:00 local time, Sweden switched from left-hand to right-hand driving (högertrafik). Some 360,000 street signs were replaced overnight after years of public information campaigns, traffic-sign manufacturing, and infrastructure work. The total cost ran to around 800 million SEK in 1967 currency. Olof Palme oversaw the operation as Minister of Communications. Initial accident rates fell because drivers were unusually cautious; rates returned to pre-1967 levels by 1969.

Dagen H was the largest civilian-logistics operation in Swedish peacetime history at the time. Sweden replaced its traffic side in a single morning, against entrenched habit, with no fatalities directly attributable to the switch. The event has become a canonical reference for Swedish state capacity: a complex, well-coordinated, statutory modernisation programme delivered to schedule.

The operation also helped build Palme’s reputation as an executive minister capable of running large projects — credentials that fed directly into his 1969 succession to Erlander. Read in that long arc, Dagen H is not merely about which side of the road one drives; it is about how Sweden chose to demonstrate that the modern state could be trusted to deliver, by morning, what it had promised for years.