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Maybe some of you will remember the Only Fools and Horses special ‘Miami Twice’, where Del Boy closely avoids a head-on collision with a car in Florida as his brother Rodney screeches at him, “You’re on the wrong side of the road! They drive on the right-hand side of the road over here!” A comedy classic that highlights that, for some, the right side of the road is anything but.

So why is it that some countries drive on the left side of the road as we do in the UK and others, like the Americans, drive on the right? This article looks into the history of this road traffic rule and explores where the modern conventions originally came from.

Confusion reigns around the world

Here in the UK we drive on the left-hand side of the road, and our cars are right-hand drive (RHD) because it’s much easier to see what’s going on. It is perfectly legal to drive a left-hand-drive car (LHD) in the UK, but it is a bit more challenging – not to mention that you are always on the wrong side for toll booths and drive-through services.

Europe is generally the opposite way around to the UK, where the cars are left-hand drive and you drive on the right-hand side of the road. Again, it’s legal to drive a UK car with the steering wheel on the right over in Europe. The main issue is headlight aiming, as your lights are angled slightly towards the kerb and away from oncoming traffic. This is why you have to fit those fiddly stickers to your headlights when driving a UK car in continental Europe, as your headlights are angled towards oncoming vehicles.

Who drives on which side of the road?

Countries like the UK that drive on the left-hand side of the road are in the minority, with 74 total territories doing so, as opposed to 167 that drive on the right. Of all the roads around the world, 90% of their total distance are ‘wrong way round’ to us.

As the map above shows, many of the RHD/left-side-of-the-road nations are members of the Commonwealth of Nations (or previously part of the British Empire), so there is a definite political dimension to which side of the road a country drives on.  Of all the current British territories, it’s only Gibraltar that doesn’t follow the left-hand rule as they drive on the right in line with the other countries in Europe.

There are a number of theories as to where the left vs. right traffic conventions have come from, but there is no definitive answer.  It is only relatively recently, with the advent of modern state regulations, that road traffic rules have been defined and recorded. So let’s explore some of the likely reasons for why countries drive on the side of the road they do.

The Roman road system – insights into ancient ways

The ancient Romans were famed for their roads, whose straightness is a characteristic that is still evident on many modern roads today. The quality of Roman roads was only surpassed during the industrial revolution many hundreds of years later. With the military importance roads had in upholding the Roman Empire across Europe, they must have had a well-ordered system of organising the roads and their traffic. So which side did they use?

The best insight to this was found in 1998 during an archaeological excavation of a Roman quarry site near Swindon. The road leading to and from the quarry site was well enough preserved for the archaeologists to clearly see that one side had grooves worn into it. As carts would enter the quarry empty and leave heavily loaded, the grooves were presumably caused by cart traffic leaving the site, meaning that (at this location, at least) the Romans traffic drove on the left.

It’s likely that the rules governing Rome’s roads were standard throughout the empire, as they were primarily a military asset; transporting columns of centurions from the Irish Sea to the Middle East. As the roads were for military purposes, the rules governing them would probably have derived from the army. A theory has been offered that the left would have been the best side to use for marching Roman troops so that the sword and scabbard, worn on the left-hand side, would not catch against troops marching in the opposite direction.

Another theory is that a left-hand side position would place the right, sword-wielding hand nearer to a potential adversary coming the other way. Throughout time, right-handed people have always been numerically dominant over left-handers, so marching and driving on the left would suit the vast majority of men.

The fall of the Western Roman Empire to the barbarian invaders ended Roman road construction in Europe and the bureaucratic system governing them. However, the barbarian invaders adopted and emulated many Roman traditions and systems, meaning that Roman influence stretched into the Dark Ages and beyond. This may have included the conventions for road or track use.

Road conventions in Medieval Europe

It seems that traffic conventions set in place by the Roman Empire continued to be followed by the kingdoms that inherited Western Europe. Evidence of this is contained in a 1300 AD papal edict by Pope Benefice which decreed that all pilgrims travelling to Rome should keep to the left.

The Roman Catholic Church inherited and continued Roman authority until the dissolution of the Holy Roman Empire in 1806. This suggests that, at least until the early 19^th Century, most of Europe had left-hand traffic like the UK. There is no military reason stated in the edict, which addresses the issue of congestion in the eternal city, but that is not to say that the convention itself did not have military ancestry.

An important aspect of medieval society to bear in mind is how superstitious it was. The Church believed that left-handedness was demonic, and left-handed people either had to adopt the right hand or face persecution or being ostracised. This means that handling of tools and weapons would be done with the right-hand side.

Another theory on the left-hand convention argues that for knights the only way to mount a horse wearing a sword on the left would be from the left and so for ease of mounting or dismounting the left side of a road would be used. In support of this are the origins of the modern military salute; lifting the right hand to the brow and dropping it. This originated with Medieval knights, who to greet each other would lift their helmets visor to identify each other.

Yet another theory adds that to approach somebody in peace, you would offer them your right hand to shake, as opposed to approaching them in anger with a sword or dagger in hand.  This is the origin of our modern western convention of shaking hands. Medieval society was highly violent; nearly everyone would have carried a side arm, bandit attacks and murders were common and so personal security would have been of prime concern.

It seems that the medieval conventions arose from a mixture of inherited Roman customs and from the social customs of a more violent society. However, as the superstitions of the Middle Ages gave way to the rationality of the Enlightenment, road conventions became more politicised.

The right-hand revolution

It was the republican revolutionaries in Europe and America who set about changing the road conventions to drive on the right-hand side. During the American War of Independence, French revolutionary the Marquis de Lafayette, the ‘hero of two worlds’ who went to fight against the British and who became a close friend of George Washington, suggested to him that the colonists adopt the right-hand traffic convention. Whether this was done immediately after the colonists’ victory in 1783 is not known, but the first record of a law on the subject is found shortly after with a 1792 Pennsylvania statute specifying to keep right.

In Europe, republican revolution came to France a few years after the Americans had won their freedom. With it came a commitment by revolutionaries to overturn the existing order and usher in a new age of reason. As part of this, there were strong anti-clergy and secular views in the ranks of the French revolution who sought to overthrow Papal authority by subverting its conventions and edicts, such as that on pilgrims in Rome.

There is also a theory that Napoleon changed the side of the road used because he himself was left-handed. However these may have contributed, during the revolutionary conquests the side of the road that was driven on became politicised.

It was Napoleon’s conquests throughout Europe that spread revolutionary ideology and overturned the existing conventions of its monarchies. As the French armies swept across Europe, they introduced the right-hand law to symbolise freeing countries from their old medieval social and political systems. Napoleon’s invasion of Austria showed this political aspect, as his armies only invaded the Tyrol in the west of the country, and only in that region was the right-hand side rule imposed.

Changing the side of the road on which people travelled was a symbolic act, meant to show the power of the new regime over all aspects of society and to place the revolutionary countries diametrically opposed to those they believed represented the values of the old world. Those powers that represented the old conservative world and resisted Napoleon’s advances – Britain, Portugal, Austria-Hungary and Sweden – all continued to keep to the left.

Napoleon’s failure to conquer all of Europe caused there to be a variety of conventions across countries. In Belgium there was no convention for which side of the road to travel on, with some regions driving on the left and some on the right. This situation was only addressed in 1899, not long after the first motor cars arrived, when the drive-on-the-right rule was imposed to bring order to an increasingly busy road system.

Although Napoleon conquered major colonial powers in Europe, the conventions in their colonies were generally not changed.  This was the case in the Dutch colony of Indonesia, where the original convention to drive on the left remained in place even after Napoleon changed the Netherlands to driving on the right (and has remained so until today).

The Right Wing revolution

As Napoleon tried to conquer all of Europe in the 18th century, so Hitler tried the same in the 20^th Century. And like his maniacal predecessor, Hitler sought to change Europe’s driving conventions. Completing the work Napoleon started, Hitler changed all of Austria to drive on the right after the 1938 Anschluss unified Germany and Austria. Next was Czechoslovakia in 1939, and during the war Hungary was changed to drive on the right in 1944.

After the Second World War, only one country in continental Europe was still driving on the left – Sweden. It changed to match its neighbours in 1967.

The colonial and anti-colonial influence

As European empires spread throughout the world, they spread their control and influence, which included imposing driving conventions on their colonised people. Britain spread the left-hand rule to the territories it colonised, but also some that it did not.

In Japan, the influence of the British ambassador Sir Rutherford Alcock led the country to start travelling on the left from 1859, a change formalised by Japan’s government in 1872. This was also the case in China, where British influence caused a similar change to the left in the important port city of Shanghai.

As much as the road conventions were a means of colonial powers to impose their rules on their territories, they were equally used by post-colonial nations to assert their independence. This was the case in Myanmar (Burma) where as one contemporary writer noted the, ‘rule of the road was recently and suddenly imposed to supersede that inherited from colonial times’. Other post-British Empire nations like Nigeria and Ghana switched to driving on the right soon after they were granted independence from Britain.

The idea of changing to driving on the right to shake off the colonial yoke was considered in Pakistan following independence; their decision not to was all down to camels. At the time the country was heavily dependent on camel trains for transportation, whose camels were training to walk on the left.  The retraining of the camels for right-hand traffic was enough of a task for the country to reconsider the move and stay on the left.

The anti-colonial impetus for changing the road conventions seems to have petered off after the initial flood of newly independent nations asserting their new found freedom and in recent years economic reasons have taken the forefront. In 2009, Samoa – previously a German colony – which drove on the right, changed to driving on the left.  This wasn’t in order to throw off the reigns of colonial power, however, but in order to benefit from cheaper car imports from Japan and Australia!

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This article was originally published in 2014, and was most recently updated in May 2021.