When the federal state of Rhineland-Palatinate was founded on 30 August 1946 by the commander of the French army on the French occupation zone Marie Pierre Kœnig, Mainz became capital of the new state.
Leta 1936 so sile Tretjega rajha z velikim pompom vkorakale v Porenje in naredile prvi korak v njegovem bliskovitem širjenju.