The origins of the Great Road are not clearly explained, but certainly it had existed since long before the founding of the Shire in III 1601. The fact that it ran from Mithlond in the west toward Rivendell in the east suggests that the route may first have been laid down by the Elves (who founded Rivendell in II 1697). Alternatively, the road is frequently associated with the Dwarves, who were well known as road-builders elsewhere in Middle-earth, and the Great Road may have had its beginnings in a trading route for that people.

After the founding of the North-kingdom of Arnor in the late Second Age, much of the road ran through the lands of the Northern Dúnedain and would have been maintained by the Men of Arnor, though the road itself seems to have predated the founding of their kingdom.

Between Michel Delving and Rivendell, the route of the Great Road is well established. Westward of the Shire, however, things are less clear. We're told that the road ran as far westward as the Grey Havens on the Gulf of Lune, but this western section of the road does not appear on any canonical map, and so it is shown here using a conjectural dashed line.