Left vs Right

Why do we drive on the left/right!?
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References: http://brianlucas.ca/roadside/

In 2009, the country of Samoa prohibited the
sale of alcohol ---- for three days ---- to

keep people safe while the island nation switched
from driving on the right side of the road

to driving on the left. The switch was so
Samoans could get cheap "hand-me-down" cars

from nearby left-side driving New Zealand
and Australia. But Samoans weren't too pleased,

since most of the cars they owned were designed
to drive on the right. In fact, 2 out of 3

earthlings drive on the right.

But why? ... There aren't clear and obvious
reasons to choose one side over the other,

so the origin of driving conventions is a
perfect opportunity for the mathematics of

game theory and symmetry breaking. Or we can
just look at historical evidence.

Today's rules evolved from "driving" livestock
and carts on the earliest roads. Archaeologists

view deeper grooves on the left lane leaving
an ancient Roman quarry in England as evidence

for left-side traffic, since departing wagons
would've had heavier loads. And it's possible

that this left side convention was in place
so right-handed soldiers and knights could

draw their weapons more quickly against passing
enemies.

Whatever the reason, keeping to the left was
eventually made into law in England in 1835.

And today, most people who drive on the left
side live in countries, like India, South

Africa, and Australia, which were once British
colonies.

But that doesn't explain why the rest of the
world drives on the right.

Some claim that following the French Revolution,
drivers there switched to the right to reject

the practices of their overthrown aristocracy,
but others suggest the French drove on the

right all along. Regardless, driving on the
right side of the road did spread across much

of Europe when Napoleon (and later Hitler)
imposed their national driving rules on conquered

territory.

And other countries voluntarily switched to
the right to align with their neighbors, like

Sweden in 1967, or to veer away from their
colonial pasts, like Nigeria and Ghana in

the 1970s.

And in the US? Well, America owes its right-sided
habit, in part, to the carts and postilion

wagons of its early days. Driving either from
the ground or from horseback, right-handed

men preferred to walk or ride on the left
side of the horses so they could control the

animals with their right hand. As a result,
they drove their wagons to the right in order

to be seated near the center of the road,
to see and steer clear of oncoming traffic.

And that's ultimately the point of driving
laws: to keep us safe from the high-speed,

two-ton metal projectiles we call cars.