WHICH SIDE OF THE ROAD DO THEY DRIVE ON?

Why do some countries drive on the right and others on the left?  Most people are right-handed, which leads to a natural tendency to favor one side of the road or another depending on the dominant means of transportation being used.  The most important factor seems to be the relative dominance of different types of animal-drawn carts and wagons.

Riding a horse: keep left.  A right-handed person finds it easier to mount a horse from the left side of the horse, and it would be difficult to do otherwise if wearing a sword (on the left).  Since it is safer to mount and dismount towards the side of the road, rather than in the middle of traffic, the horse is ridden on the left side of the road.  Also, horsemen armed with swords prefer to keep left of each other in order that their sword arm is nearer their opponent during unfriendly encounters and it is easier when riding on the left to offer one's right hand for a friendly encounter.

Jousting: keep right.  Jousting knights normally held their lances in their right hands.  It is sometimes incorrectly assumed (a common error in movies) that they approached and passed one another on the left.  In fact, jousting knights keep to the right.  The knight holds the lance in the right hand at an angle across the horse's neck.

Leading a horse, or a horse and cart, on foot: keep right.  It appears to be a universal practice that people lead horses with the right hand while walking on the left side of the horse.  To best control the horse and to avoid collisions between wide carts, it is best for the person leading the horse or cart to walk between the vehicle and oncoming traffic, thus keeping the cart or horse to the right.  This also facilitates conversations between people meeting, and it is more comfortable for the person walking to be in the relatively firm and unobstructed center of the road than the edge.

Vehicles pulled by more than one horse, driven from the vehicle: keep left.  In some places, teams of horses pulling a wagon were driven by a person sitting on the vehicle.  A right-handed driver controls the team with a whip held in the right hand, and so must sit on the far right-hand side of the vehicle, otherwise the whip will hit the vehicle and anyone else seated in it.  From the right-hand side of the vehicle the driver finds it easiest to maintain separation with oncoming traffic by keeping to the left.  It is also easier to quickly turn the team to the left than to the right if the whip is in the right hand, so it is better to keep left so that a quick left turn can be made off or to the side of the road in case of a potential collision.

In summary: The choice of sides seems to have been governed by the time of introduction of these different modes of transportation and their relative numbers.  Most often, left-side riding was the initial standard.  In areas where hand-led carts became dominant (including, presumably, France), right-side driving was adopted.  In areas where vehicles driven from the vehicle became dominant, left-side driving remained the norm.

The Roman Empire standard.  The standard was almost certainly keep left.  There is no written record of the Roman standard, but in late 1998 the remains of a Roman quarry were discovered at Blunsdon Ridge, near Swindon.  Ruts in the left side of the road are much deeper than the right, indicating that fully laden carts leaving the quarry were being driven on the left.  Also, a denarius coin from between 50 BC and 50 AD shows two horsemen riding past each other keeping to the left side of the road.

The Napolean factor.  It is unknown when France adopted right-side driving, but it is documented that Napoleon required the countries he conquered to conform to French practice.

The USA.  In the early years of English colonization of North America, English driving customs were followed and the colonies drove on the left.  The colonies gradually changed to right-hand driving after independence from England, although the northern colonies drove on the left well into the 20th century.

Canada.  Excluding French-influenced Ontario and Quebec, Canada drove on the left until the early 1920s.

 

                                     

Only one third of the world now drives on the left (based on population, rather than vehicles).  The major left-side driving countries are:

In Europe:

Cyprus

Guernsey

Ireland

Malta

United Kingdom

 

In Africa:

Botswana

Kenya

Lesotho

Malawi
Mauritius 
Mozambique
Namibia 
Seychelles
South Africa 

Swaziland

Tanzania
Uganda 

Zambia

Zimbabwe

In Asia:

Australia
Bangladesh
Bhutan
Brunei
Fiji
Hong Kong
India
Indonesia
Japan
Kiribati 
Macao
Malaysia
Maldives 
Nauru
Nepal
New Zealand
Pakistan
Papua New Guinea
Samoa (new, since 7 Sept 2009)
Singapore
Solomon Islands
Sri Lanka
Thailand
Tuvalu
In the Americas:
Antigua and Barbuda
Bahamas
Barbados
Bermuda
British Virgin Islands
Dominica
Falkland Islands
Grenada
Guyana
Jamaica
Saint Kitts and Nevis
Saint Lucia
Saint Vincent
Suriname
Trinidad and Tobago
US Virgin Islands