Selective polycentricity in the knowledge economy: CBD primacy and subcenter heterogeneity in Seoul

Metropolitan polycentricity in the knowledge-based economy represents not a simple dispersion of jobs but a qualitative restructuring of urban systems. While empirical studies on global metropolitan areas have described centralized–polycentric patterns, they have rarely examined the internal dynamics driving this transformation. Using the Seoul Metropolitan Area (SMA) from 2000 to 2020, this study analyzes how polycentricity unfolds as a multidimensional process shaped by hierarchical, functional, and spatial interactions. We first identify the hierarchical differentiation of centers, revealing strong CBD primacy and distinct subcenter heterogeneity. Second, sectoral and functional analyses show that CBD specialization and selective re-agglomeration in middle-tier centers underpin metropolitan restructuring. Finally, kernel density analysis with LQ and Theil indices demonstrates that functional differentiation has intensified directional bias and spatial inequality along the southern growth corridor. Synthesizing these results, the study proposes an integrated interpretive framework of Selective Polycentricity (SPC) —a lens explaining how CBD specialization, subcenter heterogeneity, and directional–functional alignment unfold simultaneously and interactively. The findings highlight spatial inequalities and the differentiated roles of centers in the knowledge economy, offering new insights into the qualitative evolution of global metropolitan systems. • Selective polycentricity arises from CBD specialization, heterogeneous subcenters, and directional–functional alignment. • Empirical evidence from Seoul shows the rise of middle-tier subcenters alongside the continued primacy of CBDs. • Functional differentiation followed directional growth, reinforcing spatial inequality across the metropolitan area.