The roadway that ran north to south through the Marish beside the river Brandywine. This boggy region of the Shire's Eastfarthing was unsuitable for a typical road or track, and so a raised causeway was constructed through the fenlands. Its southern extent was the landing at Mithe, where the Shirebourn flowed into the Brandywine. From there it ran northwards through the village of Rushey and on at least as far as Stock (the course of the road continued northwards to the Brandywine Bridge, and it appears to have continued as a causeway as far as its meeting with the East Road).¹

The Causeway of the Shire is not to be confused with another road, also named 'the Causeway', that ran between Osgiliath on Anduin and the Wall of the Pelennor. Though the principle was the same - to provide a dry path through marshy ground - that Causeway lay far away to the south of the Shire in the land of Gondor.