Germany continues to face an inter-regional political divide between the East and the West three decades after unification. Most strikingly, this divide is expressed in different party systems. The right-wing populist Alternative for Germany and the left-wing populist Left Party are considerably more successful in the eastern regions, while German centrist parties perform worse (and shrink faster at the ballot-box) than in the West. The article discusses empirical evidence of this resilient yet puzzling political divide and explores three main clusters of explanatory factors: The after-effects of the German Democratic Republic’s authoritarian past and its politico-cultural legacies, translating into distinct value cleavage configurations alongside significantly weaker institutional trust and more wide-spread skepticism towards democracy in the East; continuous, even if partly reduced inter-regional socioeconomic divisions and varying economic, social and political opportunities; and populist parties and movements acting as political entrepreneurs who construct and politically reinforce the East-West divide. It is argued that only the combination of these factors helps understand the depth and origins of the lasting divide.