In recent years, the phenomenon of population decline in small and medium-sized cities has emerged as one of the most pressing challenges for urban planners and policymakers worldwide. While metropolitan hubs often dominate academic discourse and policy agendas, these smaller urban centers face unique demographic and fiscal pressures that demand tailored approaches. The dynamics influencing population changes in these municipalities are complex, multifaceted, and interconnected with fiscal allocations, social welfare policies, and infrastructural development. A groundbreaking study conducted by Dr. Haruka Kato from Osaka Metropolitan University sheds new light on how specific per capita municipal expenditures correlate with population changes in Japan’s small and medium-sized cities, offering valuable insights that could reshape urban management strategies globally.
Japan, characterized by its shrinking and aging population, provides an especially pertinent context for exploring sustainable urban development amid demographic decline. Dr. Kato’s research meticulously analyzes cross-sectional data gathered from all small and medium-sized municipalities across Japan, spanning the years 2007 to 2022. Utilizing sophisticated machine learning models, particularly the eXtreme Gradient Boosting (XGBoost) algorithm, this study transcends the limitations of traditional linear methods by capturing nonlinear relationships inherent in demographic and fiscal variables. This advanced analytical framework allows for the identification of nuanced patterns that might otherwise remain obscured.
The findings reveal a stark reality: an overwhelming majority of these cities — precisely 1,288 of them, accounting for 82.56% — are experiencing population shrinkage. This is not merely a Japanese phenomenon but reflective of broader global trends where urban centers outside major metropolises grapple with diminishing residency, economic stagnation, and aging demographics. Within this context, the study explores how municipal expenditures influence these demographic trends, attesting to the critical role of city budgets in shaping urban vitality or decline.
Interestingly, the research uncovers a strong association between welfare-related expenditures and population changes. Cities that prioritize increased per capita spending on children tend to witness population growth, signaling the pivotal impact of child-centered welfare programs on urban sustainability. These investments might encompass areas such as early childhood education, childcare services, and family support initiatives, which collectively foster a conducive environment for young families and, consequently, help reverse or mitigate population contraction.
Conversely, cities that increase per capita expenditures for welfare recipients and the elderly often experience population decline. While support for vulnerable groups remains essential, this finding suggests that excessive fiscal strain in these categories may not translate into broader demographic revitalization. Instead, it possibly reflects underlying age structure imbalances or socio-economic challenges that require more holistic policy interventions beyond welfare provisioning alone. The complex interplay between supporting aging populations and ensuring demographic dynamism surfaces as a central theme in urban fiscal policy.
Beyond welfare, the study also evaluates the influence of infrastructural investments on demographic trends. Specifically, expenditures on city planning related to street maintenance and construction exhibit a tangible positive correlation with population growth. This underscores the importance of fundamental urban infrastructure in enhancing a city’s attractiveness and livability. Efficient, well-maintained road networks not only facilitate mobility and economic activity but also contribute to the quality of life, which can substantially affect residents’ decisions to remain in or relocate to these cities.
Dr. Kato emphasizes the growing relevance of adopting an urban management perspective grounded in data-driven decision-making. With municipal budgets inherently limited, strategic allocation becomes paramount. Policymakers need to discern not only how much to invest but critically where these funds will spur the most meaningful demographic and social outcomes. The evidence from this study points decisively toward prioritizing child welfare expenditures, a strategy conducive to long-term urban population sustainability.
The methodological approach itself marks a notable advancement in urban demographic research. Employing the XGBoost algorithm, a powerful ensemble learning technique, enables the analysis to account for complex, nonlinear interactions between variables that traditional econometric models might overlook. This reflects a broader trend in social science research where machine learning tools are increasingly leveraged to dissect layered societal issues with greater precision.
Urban shrinkage, particularly in small and medium cities, has often been overshadowed by the focus on managing growth in megacities. However, Dr. Kato’s research contributes to redressing this imbalance by providing empirical evidence tailored to these less-studied contexts. Such insights encourage a rethinking of generalized policy prescriptions and reinforce the necessity of locally adapted urban management solutions grounded in sound data analysis.
Furthermore, the study implicitly calls for a holistic integration of demographic, fiscal, and infrastructural dimensions in urban policy frameworks. Singular focus on any one aspect may fall short of addressing the complex realities small and medium-sized cities face. Instead, coordinated policies that harmonize welfare programs, family support, and infrastructure development could foster more resilient and sustainable urban environments.
The implications of this research extend beyond Japan, resonating with many advanced economies confronting similar demographic challenges. Aging populations, urban-rural divides, and fiscal constraints are common threads linking disparate national contexts. Policymakers internationally can draw lessons from these findings, tailoring expenditure priorities to bolster population stability and urban vitality at sub-metropolitan scales.
Importantly, Dr. Kato’s research arrives at a crucial juncture as many cities around the world grapple with post-pandemic recovery and demographic recalibrations. The emerging evidence base equips urban managers with actionable knowledge as they design policies intended not only to stabilize populations but to enhance quality of life and economic sustainability.
Ultimately, this study offers a compelling argument for reexamining how municipal funds are allocated in declining cities. It challenges conventional approaches that may overly emphasize elderly welfare spending at the expense of child-focused support and infrastructure, framing such investments as critical levers for demographic sustainability. As urban policymakers confront constrained budgets and complex social realities, research of this caliber provides a much-needed compass to guide evidence-based, strategic urban governance.
Dr. Kato’s work, recently published in the Journal of Urban Management, stands as a testament to the power of integrating advanced analytical methods with pressing urban policy challenges. Moving forward, it is imperative for further studies to build upon these findings, exploring causal mechanisms and evaluating policy interventions that embrace the multidimensionality of urban population dynamics.
Subject of Research: Not applicable
Article Title: Effective per capita municipal expenditures correlated with population changes in small and medium-sized cities in Japan
News Publication Date: 6-Mar-2025
Web References: http://dx.doi.org/10.1016/j.jum.2025.02.006
References: Journal of Urban Management (2025), DOI: 10.1016/j.jum.2025.02.006
Image Credits: Haruka Kato, Osaka Metropolitan University
Keywords: urban shrinkage, small and medium-sized cities, municipal expenditures, population change, child welfare, aging population, infrastructure investment, XGBoost, urban management, demographic sustainability, Japan
