The US has not always been a nation of right-handed drivers. Earlier in the history of the US carriage and horse traffic traveled on the left side of the road as it did in England. By the late 1700, so it is told temsters driving large wagons pulled by several pairs of horses began prompting to shift to the right side. A driver would sit on the rear left horse in order to wield his whip with his right hand. To see opposite traffic clearly, the teamsters traveled on the right side.
One of the final moves to firmly standardize traffic directions in the US occurred in the 20th century when Henry Ford decided to mass-produce his cars with controls o the left side. A reason stated in a 1908 catalog was the convenience for passengers exiting directly onto the curb, "especially...if there is a lady to be considered".
submitted by Dawn Westfall