Fulda River, river, central Germany, a tributary of the Weser River. It rises on the Wasserkuppe (mountain) in the Rhön mountains and flows generally northward past the cities of Fulda, Bad Hersfeld, Melsungen, and Kassel. The main tributary is the Eder River, which joins it from the west above Kassel. The Fulda unites with the Werra at Münden to form the Weser River after a course of 135 mi (218 km).
The river valley, flanked on the left by the Vogelsberg, Knüll, and Habichtswald highlands and on the right by the Rhön and the Thüringer Wald, served as a trade route between southern and northern Germany during the Middle Ages, and the upper course of the river formed part of the boundary between East and West Franconia before 1100. Today the Fulda basin, apart from the industrial city of Kassel, is a region of wooded hills, farms, and recreational areas including the Edersee reservoir, ski slopes, and several spas.