The history of driving

In February 2008, Donie Cassidy, the leader of Ireland’s upper chamber, the Senate, suggested that Ireland should consider giving up driving on the left side of the road. He argued that Irish economic growth over the past decade had attracted many thousands of workers and tourists from Europe and America and that the move to the right would reduce road accidents caused by foreigners.

As Cassidy observed, most European nations now drive on the right, as does the USA, while in Britain and Ireland drivers still keep to the left. But left-hand driving is not so unusual – about a third of the world drives  on the left – though many of the countries that do so are former British colonies. So how did the preference for driving on the left or right side of the road come about?

In the past almost everybody travelled in the centre of the road, shifting to the left when passing oncoming traffic. Foot soldiers and wheeled vehicles did so under the Roman Empire and the custom persisted throughout the Middle Ages. There was a practical reason for it. Swordsmen preferred to keep to the left of the road so their right arm was free to defend against potential enemies. The shift from left to right began with a change in transport technology. In the late 18th century, waggoners in America began using big carts pulled by several pairs of horses to haul their produce to market. The drivers sat on the left rear horse or on a separate horse on the left, so they could use their right arm to whip the team. Seated on the left, the drivers preferred oncoming traffic to pass on the same side so they could check they were clear of other vehicles’ wheels. So, waggoners started driving on the right and, to avoid accidents, those travelling on foot did so, too.

Revolutionary shift

A more definitive switch to the right began with the French Revolution in 1789. Travelling on the left was associated with the old aristocracy.

To keep a low profile, noblemen joined the lower classes on the right. In Paris in 1794, keeping to the right became an official traffic regulation. Afterwards, Napoleon’s armies exported the new French rule across Europe: to the Low Countries, Switzerland, Germany, Poland, Russia and elsewhere. The change to the right was adopted, one by one, by the revolutionary American states.

Britain stuck to the left-sided tradition and in 1835 the custom was enshrined in law, both at home and throughout the British Empire. Several other European states maintained the ancient preference for the left and the division between the left- and right-hand nations survived until after the First World War.