The three major subdivisions of the American zone (Greater Hesse, Bavaria and Württemberg-Baden) were declared on 19 September 1945.

A straw poll was held on 24 September 1950 in Württemberg-Baden, Württemberg-Hohenzollern and Baden regarding a merger of the three states, followed by a public referendum on 16 December 1951.

On both occasions, voters in Württemberg-Baden returned a clear majority in favour of a merger.

These two districts remain largely unchanged today as the Regierungsbezirke of Stuttgart (Württemberg) and Karlsruhe (Baden) within Baden-Württemberg.

The flag of Württemberg-Baden, adopted in 1947, was the black-red-gold tricolour flag of Germany which was later also adopted again by the new German states founded in 1949, the Federal Republic of Germany and the German Democratic Republic.