Last week in Japan was the first time I had ever driven a car on the left side of road. I spent a summer working in Dublin many years ago but I never once drove while I was there.

To be honest, I thought it was going to be more awkward than it was. But other than accidentally turning on the wipers a few times (they were on the opposite side to where turn signals typically live), it came to me pretty quickly.

I also noticed that left-hand traffic seems to impact the flow of many other things in Japan. On sidewalks, for example, people walk on the left. And on escalators, everyone stands on the left (and walks on the right), whereas the opposite tends to be true in Toronto.

Japan is also an orderly and rule-abiding place and so these conventions are widely followed. On more than a few occasions, I realized I was swimming upstream and then quickly switched sides.

What’s interesting is how this directional convention permeates so many aspects of everyday life. Which begs the question: where and when did it start? Do the "rules of the road" always influence everything else?

The answer seems to be that nobody really knows. There are many unproven theories. Some suggest that it has to do with how horses were ridden and walked, and that ~90% of people are right-handed.

But I couldn’t find anything definitive. What we do seem to know, at least anecdotally, is that once a side is chosen, it broadly impacts how people generally move around. Pay attention the next time you're on a busy sidewalk.