Urban Growth Divides: The inevitable structure of shrinking cities in urbanization evolution

Beyond the conventional focus on regional industrial decline and deterioration, the increasing prevalence of shrinking cities worldwide calls for a structural reevaluation. This study employs Zipf's law to establish a national-level quantitative empirical framework for analyzing the evolving dynamics of shrinking cities, incorporating various stages of urban life cycles. Japan offers an ideal context for analysis, showcasing a complete urban evolution within a closed system. Our findings indicate that, within the dynamics of city size distribution, the ongoing growth of large cities is accompanied by the increasing incidence of shrinking cities. We introduce the “Urban Growth Divides” hypothesis to explain the widening disparities between large and small cities. A consistent shift in the Zipf exponent shows the intensification of the divides, further amplified by demographic decline. The strong correlation between population change rates and the Zipf exponent confirms the inevitability of deepening systemic differentiation. This research underscores the necessity of analyzing shrinking cities through the lens of systemic urbanization evolution, particularly highlighting the inevitability of Urban Growth Divides driven by demographic dynamics. It advocates for strategic policy responses to the structural challenges of shrinking cities in an era of population mobility. • It adopts a transtemporal perspective on shrinking cities, emphasizing the need for a systemic reevaluation amid their growing prevalence. • It constructs a national-level, quantifiable empirical analysis framework to capture the dynamics of shrinking cities. • It suggests that shrinking cities, in the deepening "Urban Growth Divides" trend, are structural, not just industrial. • The findings indicate a significant correlation between population decline and increasing city size disparities. • The study advocates for strategic policy responses to the structural challenges of shrinking cities in an era of population mobility.