Digital transformation and urban land expansion: how E-commerce reshapes urban space in Quanzhou, China

E-commerce has become a major force driving industrial upgrading, urban expansion, and urban–rural integration. Yet it remains unclear whether classical theories of urban land expansion can adequately explain the digital era, particularly in terms of when and at what scale E-commerce begins to reshape urban space in traditional manufacturing cities. Using Quanzhou as a case study, this research integrates firm-level E-commerce data (2008–2023) with impervious-surface land-use datasets to examine how digital economic activities influence urban land expansion. Spatial analyses show that both E-commerce activity and built-up land expanded southeastward, although with different local trajectories. Urban growth in Quanzhou increasingly shifted toward infill development, while E-commerce expanded more rapidly from the southeast-central urban area into distant suburbs. Over time, the spatial alignment between transportation networks and E-commerce activity strengthened: although E-commerce initially had limited influence on urban structure, its rapid growth later promoted transport expansion toward suburban areas, reinforcing sprawl while also encouraging infill development. Threshold regression results further reveal the nonlinear effects of E-commerce on urban land expansion. Small and compact E-commerce clusters improve land-use efficiency and reduce land demand, whereas development beyond critical quantity and density thresholds generates agglomeration effects that drive outward expansion. Transportation accessibility, population, and industrial foundations significantly shape these processes, while public services show limited influence. This study extends theories of urban land expansion and digital economy–urban spatial interaction.