Until the past few centuries, it was customary for everyone to walk and ride on the left side of the road. Archeological evidence even shows that it was the custom during the time of ancient Rome. The reason for keeping to the left was simple: you never knew who you’d meet on the road during those times, or whether it would be a friend or a foe. Most people, being right-handed, wanted to make sure that their dominant hand was free to use a weapon, if necessary, and keeping potential enemies on their right helped them achieve a dominant position in case a fight broke out. Although we now think of it as a custom from the United Kingdom, this rule of the road extended throughout all of Europe. In Britain, the first legal requirement for traffic to keep on the left was issued for London Bridge in 1756. The 1835 Highway Act required all traffic everywhere to follow the rule.
In the late 1700s, though, people in America began transporting goods by the use of large wagons that required several pairs of horses. Drivers sat on the left rear horse, and they generally preferred for other wagons to pass on their left, so that everyone could be sure to keep their wheels clear of each other. Thus began the tradition of driving on the right side of the road. In 1792, a law was passed in Pennsylvania requiring that traffic between Lancaster and Philadelphia stay on the right, and by the Civil War, the rest of the American states and territories had followed. At around the same time, people in France began riding on the right side of the road as well, culminating in a 1794 rule mandating right-side driving in Paris. Some historians think that the French adopted the right-side driving rule purely to spite the English, whom they considered mortal enemies.
Make It Right
Some blame Napoleon for the spread of right-side travel. It’s said that all the European countries he conquered—Switzerland, Italy, Germany, Poland, and Spain—were converted to right-side driving, while the rest kept their left-side customs. These countries in turn spread their rules to the colonies and territories they founded or annexed. British colonies like Jamaica and India and much of Africa drove on the left, and colonies founded by France, Spain, or the United States drove on the right. Although there’s no conclusive evidence to support the Napoleonic theory, it’s true that colonial influence is a major factor in deciding which side of the road a particular country uses.
Even countries that began with driving on the left eventually changed sides, due at least in part to the invention of the automobile. By 1908, America was manufacturing the Model-T Ford with a left-side steering wheel, suitable for driving on the right side of the road, and many other car manufacturers followed suit. During the early twentieth century, many countries changed to right-side driving both to accommodate the new cars and to make border crossings easier. Countries and provinces that shared borders with several other countries were much more likely to switch their rules for the sake of homogeneity. Sweden was one of the last countries in Europe to adopt right-side driving, in 1967. Not only did all of their neighbors drive on the right side of the road, but most of the cars in the country were built for right-side driving—even the ones they themselves manufactured—so the government gave in and switched.
Islands are far less likely to have adopted the right-side switch. Many former British colonies such as the Cayman Islands, Australia, Indonesia, Jamaica, and Bermuda still drive on the left. The entire United Kingdom also still drives on the left. Even some landlocked countries have resisted the right-side switch if their neighbors all drive on the left. Mozambique, for example, a former Portuguese colony, still drives on the left. Even though Portugal itself changed sides in the 1920s, Mozambique is bordered by all left-side-driving countries. Likewise, many former British colonies in Africa have switched to right-side driving since they are bordered by former French colonies that had already changed over.
