E: Americans & Swedes once drove on the left

In the majority of countries, cars drive on the right hand side. This probably does not surprise you, and until recently I believed the amount of countries which stick to the ”wrong” side was in a tiny minority. However, after traveling around for a bit lately in the Eastern part of the Southern hempisphere, I got my passport stamped in quite a few left side driving countries. And discussions with Indian, Chinese, Malaysian, Kiwi and Aussie friends weakened my conviction. For about half a year now I have been curious about what the deal is in term of the actual division between right and left.

Today I came across Brian Lucas’ domain, with a very fascinating page on the topic answering my questions.

* 166 (69 %) of 240 registered countries or territories drive on the right, whilst 74 (31 %) drive on the left (see map)
* About and two thirds (4 billion) of the population drive on the on the right, compared to one third (2 billion) on the left.
* About 21 billion kilometers of road (72 %) is used for right hand driving, compared to about 8 billion kilometers (28 %) on the right.

The page also has historical theories, back to Medieval times, for why things turned out the way they were. I can reveal that much has to do with weapons, wagons, horse riding customs, and most right-handedness.

Some other interesting findings:

* Napoleon was the one enforcing right rule for all European countries (other than the little island west of Norway)
* Both US and Canada once had driving on the left
* In ancient Rome the rule was to go left
* There are nine countries with right side driving that have minor left side exceptions. This includes Italy, Netherlands and Spain.
* Several countries do not have the steering wheel on the opposite side of the side on which they drive. This breaks with my logic, particularly in Japan where some import cars that way intentionally for prestige.
* Boats and planes stick to the right
* The rules are different when it comes to trains
* In the UK pedestrians walk on either side
* And finally to a particular interesting example I myself noticed last semester at the University of Melbourne:

Although Australians normally keep left, the spiral stairs in the Ballieu Library at the University of Melbourne have a sign saying "keep right." This is apparently for safety reasons... The steps curve to the right, or clockwise, as you climb them, and they are very narrow on the inside of the curve. Narrow stairs are easier to climb than to descend, because people usually put only the front part of their foot on a stair and don't use their heels. Therefore, it is easier and safer to climb on the inside of the curve, and descend on the outside where the stairs are wider, meaning that one should keep to the right.