Q. Why, since we drive on the right of the road in this country, do American drivers insist on sitting on the right-hand side just as the English do? I can understand the English sitting on that side to get the best view of oncoming traffic, but for the same sensible reason should not American drivers sit on the left?
A. In fact there was no “rule” on the subject, people simply did what seemed the most practical to them. The whip is usually carried in the right hand and, if someone is sitting beside you, it can only be used effectively if you sit on the right. When a driver sat alone, as on an omnibus, some commercial vehicles, Hansom cabs, etc., he often sat in the middle. In England some delivery men sat on the left because then they could step off at the side of the road to make deliveries. Some French carriages were fitted with a driver’s wedge-shaped cushion that could be placed on the right-side or in the middle and held there by a short post that fitted into an appropriately placed hole in the underside of the cushion. If you look at old prints or photographs of street scenes in America you will see that here, too, some coachmen sat in the middle when they had no groom beside them. This kept the carriage on an even keel.
From The Carriage Journal, Vol. 21, NO 2, Autumn 1983