Why do some countries drive on the left? The short answer is history, not engineering. Keeping left was a common habit in the age of horses, Britain wrote it into law and carried it across its empire, and most of the rest of the world later settled on the right, pulled along by France, the United States and the car industry. Once a country has built its roads, signs and cars around one side, changing is hard and expensive, so the split has lasted.
Today about 75 countries and territories drive on the left and about 165 on the right. The left-driving group covers roughly a third of the world’s population and about a quarter of its roads. Here is how that happened, which parts of the story are well documented, and what it means if you are about to drive on the “wrong” side.
Where keeping left came from
The most often repeated explanation goes back to riders on horseback. Most people are right-handed, so a rider keeping left had the sword arm towards anyone coming the other way. A right-handed person also mounts a horse from its left side, which is easier from the edge of the road than from the middle.
It is a tidy story, but treat the older claims with care. A study of wheel wear on kerbstones in Roman Pompeii found that carts mostly drove down the middle of the street and kept right where there were two lanes. Another popular claim, that Pope Boniface VIII told pilgrims in 1300 to keep left, has no documented evidence behind it. What we can say is that before traffic became heavy, local custom decided, and it varied.
How Britain made it law
Britain’s habit became a rule in stages. The London Bridge Act of 1756 told carriages leaving London to use the east side of the bridge, which may be the first legal requirement to keep left. Keeping left was then made mandatory across Britain in 1835, and Ireland followed with its own nationwide law in 1836.
The British Empire spread the rule. That is why Australia, New Zealand, India, Pakistan, South Africa, Kenya, Malaysia, Singapore and many Caribbean and Pacific islands still drive on the left. In Europe, only four countries do so today: the UK, Ireland, Cyprus and Malta.
Why most of the world went right
France and continental Europe
Paris brought in an official keep-right rule in 1794, in the years after the French Revolution, and Denmark had made right-hand driving compulsory in 1793. Russia was earlier still, with an edict to keep right in 1752. The story that Napoleon personally switched France and then imposed the right on the countries he conquered is widely told, but historians have found no documents to prove it. What is clear is that by the 1800s much of continental Europe kept right, while Britain, Portugal and Austria-Hungary kept left.
The United States and the wagon driver
In the late 1700s, teamsters in the United States and France hauled goods in large wagons pulled by several pairs of horses. The driver sat on the left rear horse and, from there, preferred oncoming traffic to pass on the left so that it was easier to judge the gap. So wagons kept right. This explanation is common, though the evidence for it is thinner than its popularity suggests.
The laws are better recorded. Pennsylvania passed the first keep-right law in 1792, for the turnpike between Philadelphia and Lancaster. New York followed in 1804 and New Jersey in 1813.
Henry Ford’s steering wheel
Most American cars built before 1910 actually had the steering wheel on the right. Ford’s Model T of 1908 put it on the left, which suits driving on the right, and by 1915 other makers had followed. Mass-produced American cars designed for right-hand traffic then gave other countries a practical reason to pick the same side.
Countries that switched sides
In 1919 the world was evenly split, with 104 territories on each side. Between 1919 and 1986, 34 left-driving territories moved to the right. A handful went the other way.
| Country or region | When | Change |
|---|---|---|
| Canada (British Columbia and Atlantic provinces) | 1920 to 1924; Newfoundland in 1947 | Left to right |
| Portugal | 1928 | Left to right |
| Sweden | 3 September 1967 | Left to right |
| Iceland | 26 May 1968 | Left to right |
| Myanmar | 1970 | Left to right |
| Nigeria | 1972 | Left to right |
| Ghana | 1974 | Left to right |
| Okinawa, Japan | 30 July 1978 | Right back to left |
| Samoa | 7 September 2009 | Right to left |
Sweden’s Dagen H
Sweden’s switch is the most famous. Its neighbours all drove on the right, and around 90% of Swedes already drove left-hand-drive cars, which made overtaking on narrow roads risky. Even so, in a 1955 referendum about 83% voted to stay on the left. Parliament approved the change anyway in 1963.
On Sunday 3 September 1967, known as Dagen H, non-essential traffic was banned in the early hours. At 4:50 am vehicles stopped and carefully crossed to the other side, and at 5:00 am they set off again on the right. Around 350,000 road signs had to be changed. Accidents fell at first, but by 1969 rates were back to where they had been before.
Samoa goes the other way
Samoa had driven on the right since its time as a German colony. On 7 September 2009 it moved to the left so that it could import cheaper cars from Japan, Australia and New Zealand, which all drive on the left. The plan drew large protests, and the switch day and the day after were made public holidays.
Why Japan drives on the left
Japan was never a British colony, yet it drives on the left. The custom dates back to the Edo period (1603 to 1868). It gained official standing in 1872, the year Japan’s first railway was built with British technical help, and was written clearly into law in 1924. Okinawa drove on the right under US administration after the Second World War and switched back to the left at 6 am on 30 July 1978.
Why don’t the last left-driving countries just switch?
Cost and safety. Sweden had about 1.5 million cars when it changed, and it still needed four years of public education, thousands of new or rebuilt buses and a nationwide traffic ban. The UK looked at switching in the late 1960s and decided it would be unsafe and too costly. With far more vehicles, junctions and motorways today, the case is weaker still. Island nations such as the UK, Japan, Australia and New Zealand also have few or no land borders where the two systems meet, so there is less pressure to change.
What to do if you are driving on the other side
If you are visiting from the US or Canada and hiring a car in the UK, Ireland, Australia or New Zealand, or going the other way, a little planning helps.
- Learn the basic rule. In Great Britain, Highway Code rule 160 says you should keep to the left once moving, unless signs or markings say otherwise.
- Know the roundabout rule. Highway Code rule 185 says to give priority to traffic approaching from your right.
- Expect the driver’s seat to move. Countries that drive on the left almost always use cars with the steering wheel on the right, and the reverse.
- Check the local rules before you go. The UK government advises drivers heading abroad to check speed limits, drink-driving laws and required equipment for each country, and whether an international driving permit is needed.
- Check your hire car insurance. Hire cars include insurance, but it is worth checking exactly what is covered.
Our guides cover the paperwork in more detail: driving in the USA with a UK licence, whether US drivers need an International Driving Permit in Europe, and the Crit’Air sticker for driving in France.
FAQ
How many countries drive on the left?
About 75 countries and territories, compared with about 165 that drive on the right. They account for roughly a third of the world’s people. They include India, Indonesia, Pakistan, Japan, the UK, South Africa, Thailand and Australia.
Did Napoleon make Europe drive on the right?
It is a popular story, but there is no documentary proof that he ordered it. Paris had a keep-right rule from 1794, and right-hand driving spread across much of continental Europe in the years that followed.
Is driving on the left safer?
The sources reviewed for this article do not show that either side is safer. Sweden saw fewer accidents just after its 1967 switch, but rates returned to earlier levels within about two years, which suggests extra caution, not the side of the road, made the difference.
Bottom line
Some countries drive on the left because of old habits that Britain turned into law and spread around the world. Others drive on the right because France, the United States and the early car industry pulled that way. Neither side is “correct”. Each country simply kept, or was pushed into, one system, and the cost of changing now keeps the map as it is. If you are about to drive on the unfamiliar side, read the local rules first and take the first few junctions slowly.
Sources
- WorldStandards: Why do some countries drive on the left and others on the right?
- WorldStandards: List of left- and right-driving countries
- Wikipedia: Left- and right-hand traffic
- Wikipedia: Dagen H
- GOV.UK: The Highway Code, using the road (rules 159 to 203)
- GOV.UK: Driving abroad
