Emerging megaregions and intensifying spatial polarization in South Korea: Evidence from nighttime light data (1992–2020)

This study investigates the spatio-temporal evolution of spatial structure in South Korea, with the aim of understanding how spatial polarization and regional restructuring have unfolded over the past three decades. To achieve this, we apply Contour Tree Mapping and Emerging Hot Spot Analysis to Nighttime Light data. This study reveals three major findings. First, metropolitan areas such as Seoul and Busan continue to dominate the national urban hierarchy, demonstrating strong path-dependent development. Second, the expansion of cold-spot clusters in provinces including Gangwon-do and Jeollabuk-do highlights the growing marginalization of peripheral regions, signaling intensified spatial polarization. Third, a structural shift is underway as metropolitan areas increasingly conurbate, with corridors such as Seoul–Daejeon and Daegu–Busan forming megaregional configurations. This study contributes to offering empirical evidence of ongoing spatial transformation in South Korea and expands the theoretical discussion on spatial restructuring and regional development. • Analyzes spatial restructuring (1992–2020) of South Korea using Nighttime Light data and spatio-temporal spatial analysis. • Reveals path-dependent metropolitan dominance and intensifying conurbation into emergent mega-regions. • Identifies deepening spatial polarization between core regions and peripheral areas, including emerging intermediate decline. • Provides new empirical evidence linking mega-regionalization to long-term uneven regional development.