The Historical Divide
Historically, most traffic traveled on the left. In feudal societies, violent encounters were common. Since most people are right-handed, traveling on the left kept a person's sword arm free to face oncoming strangers.
The shift to the right side is largely attributed to large wagons in France and the US in the 1700s. These wagons had no driver's seat; the driver sat on the left rear horse to keep their right arm free to whip the team. To judge oncoming traffic clearances, they moved to the right side of the road.
Major Left-Driving Nations
- United Kingdom
- Australia and New Zealand
- Japan
- India
- South Africa
- Thailand
- Cyprus
Engineering the Switch at Borders
When countries with different traffic rules share a land border, complex engineering is required to switch traffic safely.
The Lotus Bridge: Connecting Macau (left-hand traffic) and Hengqin Island, mainland China (right-hand traffic). The bridge features a looped interchange that seamlessly flips cars to the correct side without intersecting traffic streams.
Thailand and Bordering Nations: Thailand drives on the left, but borders Myanmar, Laos, and Cambodia, which all drive on the right. Border crossings often use traffic light-controlled intersections where lanes physically criss-cross.