The Shirebourn is a lesser river of the Shire's Eastfarthing. Its source was in the uplands of the Green Hill Country, from where it flowed south and then southeast. At Willowbottom, it met the Thistle Brook, and then flowed eastwards until the Shirebourn itself met the Brandywine.
According to Nomenclature, Shirebourn means "Bright-stream". However, in most translations, it is translated "River of the Shire" instead.