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.
Trier (region)
After the Second World War the French military government several times extended the Saar area before forming the Saar Protectorate, also including additional 109 municipalities belonging until July 1946 to the Trier Region and some to the Koblenz Region. Koblenz Region's former areas make up part of today's St. Wendel district in the Saarland. In December 1946, when a new customs boundary dissected the Saar Protectorate (later becoming the Saarland) from the area under the Allied Control Council over Allied-occupied Germany, the Trier Region with its then remaining territory had become one of the then five regions forming the new state of Rhineland-Palatinate, founded in August 1946. Later, the French occupation government again redeployed some municipalities – some returned to Allied-occupied Germany, some newly annexed to the protectorate – between the Saar area and the new state of Rhineland-Palatinate in 1947 and 1949, before the border was finally fixed.