Why Do We Drive on That Side of the Road?

By Commonplace Fun Facts on July 25, 2019 • ( 2 Comments )

If you drive on the right side of the road, it feels perfectly natural to you. That’s the way you were taught. It’s how everyone around you drives (well, except for the idiots who shouldn’t be behind the wheel in the first place). As natural as it feels, those who drive on the left side of the road feel exactly the same way about their traffic customs. Have you ever wondered why we drive on the side that we do and why it differs from country to country?

Most of the world — about 65% — drives on the right. The countries that drive on the left are primarily the United Kingdom and its former colonies. Notable exceptions are the former colonies of the United States and Canada, which have embraced right-handed driving. The following map shows which countries follow each custom.

When the practice of staying on one side of the road began, it had less to do with traffic safety than it did personal protection. When a traveler was walking or riding on a horse, he had to remain vigilant and ready to defend himself if the traveler coming toward him had ill intentions. It was a good practice, therefore, to keep to the side of the road that would place one’s sword-wielding hand closest to a prospective opponent. Since most people are right handed, this meant traveling on the left side of the roadway. Since a right-handed person typically wears his sword on the left of his waist, this practice also prevented the scabbard from hitting people as they passed by.

Staying to the left had other safety benefits as well. A right-handed person finds it easier to mount a horse from the left side of the horse, and it would be very difficult to do otherwise if wearing a sword on the left. It is safer to mount and dismount towards the side of the road, rather than in the middle of traffic, so if one mounts on the left, then the horse should be ridden on the left side of the road.

Recognizing the benefits to uniformity for traffic patterns, Pope Boniface VIII issued the first known traffic law on this topic in 1300, mandating left-handed traffic.

With all the benefits of left-side traffic, why does most of the world drive on the right, and how did they ever start this practice? The answer to these questions take us to the late 18th century. In the United States and France, farm products began being delivered in large wagons pulled by several pairs of horses. The driver did not sit on a seat in the wagon, but rather positioned himself on the left rear horse. By sitting there, the driver could use his right arm to lash the team and keep them under control. Since the driver was on the left side, it was much easier and safer to drive on the right side of the road, thus allowing a better view to insure that the wagon’s wheels kept clear of any passing or oncoming traffic.

The side on which a traveler traversed remained largely a matter of personal preference until the 18th century. In 1752, Empress Elizabeth of Russia issued the first official traffic regulation for right-handed traffic. In 1793, Denmark joined the ranks of right-handed traffic, followed by France the year after that.

The United States officially adopted right-handed traffic in 1792 for the Philadelphia and Lancaster Turnpike. By the early 19th century, all of its states had officially proclaimed right-handed traffic for their roads. Today, there is only one holdout for left-handed traffic for United States’ territories: the U.S. Virgin Islands continues to follow the practice of the surrounding islands and drives on the left side of the road.

Now that we no longer carry swords or have to be nearly as concerned about encountering bands of roving thieves, there is no “right” answer to which side should be used, as long as everyone has the same understanding of what their obligations are. As you can imagine, however, driving in a country with a different practice than what you are accustomed to can be confusing and potentially dangerous.

On August 5, 1987, actor Matthew Broderick was involved in a deadly car accident in Northern Ireland, where he was vacationing. Shortly after completing his film Ferris Bueller’s Day Off, he rented a car to be able to take in the sights of Ireland. Broderick got confused and drove on the right side of the road. His vehicle collided head-on with another car, driven by a 63-year-old mother and her 30-year-old daughter. Both women were killed on impact.

Signage and carefully-engineered traffic flow designs at international borders help direct drivers to the proper side of the road whenever there is a switchover from one side to the other.