Boundary restructuring reshapes land use: The impact of administrative division adjustment on urban land use efficiency

Improving land use efficiency is a global consensus for sustainable urban transformation, but the powerful role of widely implemented administrative division adjustments remains insufficiently understood. Based on panel data from Chinese cities between 2003 and 2019, this study employs multi-period difference-in-differences and mediating effect models to analyze how county-level administrative division adjustments (cADC) affect urban land use efficiency (ULUE). Theoretically, cADC negatively influences ULUE by redrawing boundaries to enable urban expansion, while simultaneously undermining spatial continuity and functional coherence. The realignment of intergovernmental authority and fiscal relationships further exacerbates interjurisdictional competition for land resources and distorts land use planning, thereby diminishing social equity and cross-regional environmental governance. These institutional changes at the macro level manifest as micro-level inefficiencies in land use through resource allocation mechanisms and market processes. Empirically, cADC reduces ULUE by approximately 12%, with the strongest negative effects observed in county-to-district conversions and medium-sized cities. Although cADC stimulates labor and capital inputs, these fail to improve ULUE. Moreover, cADC significantly depresses land marketization, exacerbating efficiency losses. These findings highlight the need to carefully assess the spatial and institutional consequences of administrative restructuring. Policymakers should strengthen cross-jurisdictional coordination, harmonize public interventions with market forces, and emphasize land use efficiency rather than areal expansion to advance intensive and sustainable urban development.