Left-hand traffic (LHT) is a road system where vehicles drive on the left side of the road and typically overtake on the right. About 75 countries and territories use this system, covering roughly 35% of the world’s population and one-quarter of its roadways. The remaining 160-plus countries drive on the right.
How Left-Hand Traffic Works
In a left-hand traffic country, you drive on the left side of the road, and oncoming vehicles pass you on your right. Cars are designed with the steering wheel on the right side of the cabin, called right-hand drive (RHD), so the driver sits closer to the center of the road. This positioning gives the driver a better view of oncoming traffic when overtaking. Roundabouts flow clockwise, and highway on-ramps merge from the left.
The pedal layout inside the car stays the same regardless of which side the steering wheel is on: accelerator on the right, brake in the middle, clutch (if manual) on the left. What changes is the gear stick, which sits to the driver’s left in a right-hand drive vehicle instead of to the right.
Why Some Countries Drive on the Left
Driving on the left is actually the older convention. In the Middle Ages, most travelers were right-handed, so riding on the left side of the road kept the sword arm free to defend against oncoming strangers. Archaeologists have found evidence that Romans drove carts and wagons on the left, and Roman soldiers marched on the left side of the road. In 1300, Pope Boniface VIII made it official by declaring that all pilgrims traveling to Rome should keep left.
The same defensive logic shaped architecture. Most spiral staircases in Norman castles wind clockwise going upward, giving right-handed defenders above the advantage of a free sword arm while attackers climbing the stairs were blocked.
So if keeping left was the default for centuries, why does most of the world now drive on the right? The shift began in continental Europe during the late 1700s and accelerated under Napoleon, whose armies and territorial expansion spread right-hand traffic across much of the continent. Countries under French influence adopted the right side, while those with British colonial ties, including India, Australia, and much of East Africa and Southeast Asia, kept the left. That colonial divide is still the primary reason the map looks the way it does today.
Where Left-Hand Traffic Is Used
The largest LHT countries by population are India, Indonesia, Pakistan, the United Kingdom, and Japan. Australia, South Africa, Thailand, Malaysia, Kenya, and New Zealand are also major left-driving nations. In Europe, the UK, Ireland, Cyprus, and Malta drive on the left. Singapore, Hong Kong, and Macau follow the system in Asia, while Jamaica and Barbados are among the Caribbean nations that do.
South America is almost entirely right-hand traffic. The only two exceptions are Suriname and Guyana, both on the continent’s northern coast, reflecting their former colonial ties to the Netherlands and Britain respectively.
Countries That Switched Sides
Several countries have made the dramatic transition from one side to the other. The most famous example is Sweden, which switched from left to right on September 3, 1967, in an event known as Dagen H (short for Högertrafik, meaning “right-hand traffic”). The change was driven by a practical safety problem: most Swedish cars already had left-hand drive steering wheels, designed for right-side roads, but the country’s roads were still left-hand traffic. That mismatch made overtaking dangerous because the driver sat on the wrong side to see oncoming vehicles clearly.
The switch was deeply unpopular. A 1955 referendum showed 83% of Swedes opposed it. The government went ahead anyway, and the entire country changed over in a single day. Traffic stopped completely at 1:00 AM, vehicles repositioned to the right side of the road, and driving resumed at 5:00 AM. Accident rates actually dropped briefly after the switch, likely because everyone was driving more cautiously.
Other countries that switched from left to right include several former Swedish and British colonies. Transitions in the opposite direction, from right to left, are extremely rare.
Practical Differences for Travelers
If you’re visiting a left-hand traffic country from a right-hand traffic one, the biggest adjustment is at intersections and roundabouts. Your instinct to look left first before crossing a street can be dangerous, because in LHT countries the nearest lane of traffic comes from your right. London famously paints “LOOK RIGHT” on the pavement at pedestrian crossings for exactly this reason.
Driving takes more conscious effort. Turns feel reversed: left turns are simple (staying on your side of the road), while right turns cross oncoming traffic. Highway exits appear on the left. If you’re driving a left-hand drive car in a left-hand traffic country, overtaking becomes particularly tricky because you can’t see past the vehicle ahead of you without leaning across the cabin.
At borders where two systems meet, such as the crossings between Thailand (left) and Laos or Cambodia (right), or between Hong Kong (left) and mainland China (right), traffic must physically change sides. These transitions are handled with interchange bridges or flyovers that route traffic from one side of the road to the other without requiring drivers to cross oncoming lanes. The Lotus Bridge connecting Macau and mainland China is one well-known example, using a looping overpass to make the swap.