Why some countries drive on the left and others don’t

Roughly 35% of the world’s population drives on the left, and almost all of those countries share one thing: they were once British colonies or territory. In Europe, only the United Kingdom, Ireland, Cyprus and Malta still keep to the left. The most repeated explanation of where it began involves swords, and it’s shakier than it sounds.

If you’re renting a car abroad, what matters is simple: in the UK, Ireland, Australia and other left-hand countries, the steering wheel is on the right and everything flips, roundabouts included.

The sword theory, and what we can actually say

The popular story says that in the Middle Ages, riders preferred the left side of the road so their right arm, the sword arm, faced anyone coming the other way. It’s a hypothesis repeated in popular history writing, but no documentation fully confirms it. I treat it as plausible, not as fact.

Another reason shows up more firmly in the sources. In the late 1700s in the United States and France, drivers of heavy freight wagons sat on the rear left horse to keep their right hand free for the team, which pushed them to the right side of the road. The French Revolution, which ended the aristocracy’s privilege of using the left, and Napoleon’s conquests spread right-hand traffic across continental Europe. Countries that resisted him, like Britain, kept the left.

Britain made the left the rule in 1835

A British law of 1835 standardised left-hand traffic, and the empire carried the rule to India, Australia and Africa. The United States, newly independent, went the other way and adopted the right.

Sweden: Dagen H, 1967

The most famous switch is Sweden’s. The country drove on the left, but its neighbours Norway and Finland drove on the right, and many Swedish cars already had the steering wheel on the left. In a 1955 referendum, 83% of Swedes voted against changing. The government went ahead anyway.

On 3 September 1967, “Dagen H” (the H is for högertrafik, right-hand traffic), non-essential traffic was banned overnight. At 4:50 a.m. every vehicle stopped and, at 5:00, moved to the right. On the first day, Sweden recorded 157 accidents, mostly minor and below the usual daily rate. Road deaths fell from 1,313 in 1965 to 1,077 in 1967.

Samoa: switching to the left in 2009

The reverse happened on 7 September 2009, when Samoa moved from the right to the left. It was the first country to switch sides in nearly 40 years, according to Al Jazeera. The reason wasn’t historical, it was economic: about 170,000 Samoans live in Australia and New Zealand, more than the roughly 180,000 who live in Samoa, and they send home cheaper used cars with right-side steering wheels.

The government declared a two-day holiday, banned alcohol sales for three days and cut the speed limit from 56 to 40 km/h. Bus companies threatened to strike because the government wouldn’t pay to move the exit doors to the other side.

What to do about it

• Rent an automatic the first time, if you can. You’ll be busy enough with which side of the road you’re on.
• Remember the driver sits near the centre line. Pulling out of a car park or an empty street is when wrong-way mistakes happen.
• At roundabouts, enter on the left and go clockwise. Give way to traffic already on it, which comes from your right.
• On foot, look right first, where the nearest car comes from.

If you’re getting around London on the Tube, there’s a local rule for the escalators too: see why Londoners stand on the right on escalators.

Frequently asked questions

Why does the UK drive on the left?

The most common explanation goes back to the Middle Ages and the sword arm, but it’s a hypothesis. What is documented is that a British law of 1835 made the left the rule and that the empire spread it.

Which European countries drive on the left?

The United Kingdom, Ireland, Cyprus and Malta.

How many countries have switched sides?

Very few recently. The best-known cases are Sweden in 1967, which moved to the right, and Samoa in 2009, which moved to the left and was the first country to switch in nearly 40 years, according to Al Jazeera.

Does Brazil drive on the left or the right?

On the right, like most of the Americas.

Sources

• Driving on the left, World Standards, updated January 2026: the 35% estimate, the four European countries, the sword theory, the wagon drivers, the French Revolution, Napoleon and the 1835 British law.
• Sweden switches sides of the road, Popular Science: the 1955 referendum (83% against), Dagen H on 3 September 1967, the 157 accidents and the road deaths in 1965 and 1967.
• Dagen H: The Day Sweden Switched Traffic Sides, Amusing Planet, 2019: the 1 a.m. to 6 a.m. ban on non-essential traffic and the stop (4:50 a.m.) and restart (5:00 a.m.) times.
• Samoa set to switch road lanes, Al Jazeera, September 2009: the 7 September switch, the holiday, the alcohol ban, the speed limit and the buses.