Rhineland-Palatinate
The state of Rhineland-Palatinate was founded shortly after the Second World War on 30 August 1946. It was formed mainly from the southern part of the Prussian Rhine Province (the "Regierungsbezirke" of Koblenz and Trier), from Rhenish Hesse, from the western part of Nassau and the Bavarian Rhenish Palatinate minus the county of Saarpfalz. The Joint German-Luxembourg Sovereign Region ("Gemeinschaftliches deutsch-luxemburgisches Hoheitsgebiet") is the only unincorporated area of the state of Rhineland-Palatinate. This condominium is formed by the rivers Moselle, Sauer, and Our, where they run along the border between Luxembourg and Rhineland-Palatinate or the Saarland.
Hesse
After World War II, the Hessian territory west of the Rhine was again occupied by France, whereas the rest of the region was part of the US occupation zone. The French separated their part of Hesse from the rest of the region and incorporated it into the newly founded state of Rhineland-Palatinate (Rheinland-Pfalz). The United States, on the other side, proclaimed the state of Greater Hesse ("Groß-Hessen") on 19 September 1945, out of Hesse-Darmstadt and most of the former Prussian province of Hesse-Nassau.