As always, Wikipedia has a page on just about everything: https://en.wikipedia.org/wiki/Right-_and_left-hand_traffic#History https://en.wikipedia.org/wiki/Right

As always, Wikipedia has a page on just about everything: https://en.wikipedia.org/wiki/Right-_and_left-hand_traffic#History https://en.wikipedia.org/wiki/Right-_and_left-hand_traffic#H... ``In 1998, archaeologists found a well-preserved track leading to a Roman quarry near Swindon, England. The grooves in the road on the left side (viewed facing down the track away from the quarry) were much deeper than those on the right side. These grooves suggest that the Romans drove on the left, at least in this location, since carts would exit the quarry heavily loaded, and enter it empty.''