In Japan, do the cars drive down the left side of the road, as in Britain, or the right side, as in the USA?

The tradition of keeping to the left in Japan has deep historical roots that predate the automobile by centuries. The most widely accepted origin traces back to the age of the samurai. As most people are right-handed, a samurai would wear his long sword, or katana, sheathed at his left hip to allow for a quick draw. By walking on the left side of a road, his sword's scabbard would be on the outside, safely away from oncoming foot traffic. An accidental clash of scabbards was considered a serious provocation that could easily escalate into a duel, so this custom became an important social convention for keeping the peace.

This long-standing practice was solidified during Japan's rapid modernization in the late 19th century. The country received significant technical assistance from Great Britain in building its first national railway system. Since the British drive on the left, they designed the new train network (Review) to run on the left track as well. This decision reinforced the existing custom and set the precedent for all forms of modern transportation.

While the samurai are long gone, their legacy lives on in Japan's traffic patterns. The informal rule was officially written into law in 1924, cementing the nation's place among the roughly one-third of the world's countries where drivers keep to the left. It's a fascinating example of how an ancient martial custom was carried forward into the modern industrial age.