The (Western) Palatinate, including Kallstadt, remained Bavarian until after the end of World War II, when the German states were formally reorganized after becoming virtually defunct under the Nazi regime, when Kallstadt belonged to the Gau Westmark. The Palatinate was separated from Bavaria in 1946 and became a part of the new State of Rhineland-Palatinate, a founding state of the Federal Republic of Germany. A referendum to restore the union of the Palatinate and Bavaria failed in 1956, and Kallstadt continues to belong to Rhineland-Palatinate.