The post-urbanization of Tokyo : its spatio temporal geography and governance
Authors:   , Tateishi Eigo 
Published: December 2024

The urbanization of the global population could lead human societies to both declining and aging populations. This is because mature urban societies tend to provide urban dwellers, especially females, with better educational and work opportunities, reproductive health services, and freedom of life planning, which could result in a considerable decrease in national fertility rates. Under such societal improvements, 26–33 out of 48 global megacities, large urban regions with populations of over 10 million, will be situated in countries whose national population is projected to decrease by 20–50% by 2100. Amid such a substantial and sustained national population shrinkage, even megacities will not be free from urban shrinkage. In other words, mature urban societies will shift to the phase of ‘after’ urbanization—post-urbanization.

Considering the rather realistic scenarios of post-urbanization, it will increasingly become a significant task for urban scholars and urban policymakers to explore and understand how the decline of highly urbanized societies will potentially change mature urban societies and how they are governed. Yet, the field of urban studies remains underdeveloped in terms of both academic and policy attention and foundational empirical research on post-urbanization. This thesis seeks to address this gap. Specifically, its overarching aim is to envisage what post- urbanization could bring to urban societies in the 21st century and propose policy propositions for future scholars and policymakers.

To achieve the given aim, this thesis, as one of the initial scientific research efforts, explored the post-urbanization of the Tokyo Capital Region, the world’s largest megacity projected to become the first declining megacity by 2030, both in theoretical and empirical terms. In the theoretical exploration, relying on and revising existing relevant theories, this thesis discusses how demographic factors will increasingly play a constitutive role in urbanization and urban governance during a phase of constant and total population loss. In the empirical exploration, following a mixed-method research design integrating various methods— interviews, text-mining, spatial explorative analysis, and machine learning, the thesis yielded three articles analyzing the changing patterns of urbanization and urban governance of Tokyo.

The first article using machine learning captured how the spatiotemporal socio- demography in Tokyo has been transforming into a complex heterogeneous landscape of (re)urbanization, (post)suburbanization, and urban shrinkage, illustrating that the spatial distribution of demographic resources increasingly becomes uneven within the megacity region. The result suggests that as post- urbanization progresses, inter-municipal disparities in demographic prosperity will increase, hindering municipalities from forming metropolitan governance.

The second article drawing on interviews and quantitative spatiotemporal explorative analyses revealed that in the shrinking suburbia of Tokyo, demographic factors, through changing policymakers’ perspectives, have been influencing the mode of urban governance and resulting policies. While the empirical findings confirmed that forming a shrinkage-preemptive mode of metropolitan governance is possible, reinforcing both vertical and horizontal coordination across public authorities will be essential to promote it.

The third article using a text-mining technique supports the existing arguments that bundles of locational preference among re-urbanizing socio-demographic groups are crucial to explain urban regrowth. For urban policymakers, this suggests strategic bundling of different urban features—physical structure, urban amenities, and place images—will be crucial to effectively attracting new residents. Even for policymakers in prosperous localities, to maintain demographic prosperity, it will remain important to monitor the changing metropolitan landscape of locational preferences to strategically adjust their bundles of urban features.

Based on the given theoretical discussions and empirical insights, the thesis concludes that post-urbanization will bring a complex and heterogeneous post- urban landscape with uneven demographic prosperity where conventional growth-based urban governance and policies will be increasingly ineffective, and cooperative metropolitan governance will be essential to manage post-urban challenges. Yet, simultaneously, the study argues that the uneven distribution of demographic wealth per se, inducing inter-municipal competition, will increasingly hinder the localities in the megacity from realizing such metropolitan governance.

Reflecting on these insights, the study formulated four policy propositions that are primarily for Tokyo but can potentially apply to future post-urban megacities. First, national and prefectural governments need to actively form institutional settings that enable and encourage megacity municipalities to coordinate different counter-shrinkage policies with their neighbors. Second, policymakers, together with relevant non-public stakeholders, need to form a policy-driven coalition to cooperatively manage and maintain inter-municipal physical and/or social infrastructures that are essential for maintaining their demographic prosperity. Third, policymakers, particularly those in the shrinking suburbs of the megacity, should strategically implement region-wide place branding to strengthen the region's socio-economic autonomy, retain current residents, and actively attract new ones, while also fostering inter-municipal governance.

Finally, as actors—both public and non-public—largely determine the mode of governance and resulting policies for post-urban challenges, whether cities can realize the given three propositions and thus maintain and attract demographic wealth will depend heavily on what kind of people live and work in the city. Hence, effective post-urban governance, although this sounds pessimistic, is not something all post-urban localities can achieve. This implies that policymakers need to embrace the reality that in post-urban societies, some cities without the right people at the right moment will need a lot of effort to avoid their demise. After all, in post-urban societies where people are the underlying wealth of prosperity, people do matter.