Urbanization trajectories are weakly constrained by initial conditions in a late-urbanizing region

Population growth and rural–urban migration drive urbanization processes that reshape land cover, energy demand, and environmental pressures. In regions experiencing late-stage urbanization, these processes unfold unevenly across administrative units and ecological contexts, challenging the assumption of homogeneous urban growth and uniformly negative environmental impacts. However, empirical assessments that integrate demographic, spatial, and energy dimensions at fine spatial scales remain scarce, particularly in developing regions. We examine long-term urbanization dynamics across 117 administrative units in Northwest Argentina between approximately 1985 and 2020, a region characterized by high ecological and demographic diversity. Using population census data, multitemporal Landsat-derived urban land cover classifications produced through supervised random forest models, and official electricity consumption records, we quantify initial conditions, temporal trends, and spatial heterogeneity in urbanization-related processes across contrasting ecological regions. The results reveal strongly differentiated urbanization trajectories. Highly urbanized core units show decelerating growth as they approach spatial and demographic saturation, whereas adjacent units experience accelerated expansion, which is consistent with urban sprawl and metropolization. Less populated units display highly variable pathways, ranging from rapid urban growth to stagnation and demographic decline. Urban pressures vary across ecological regions, with humid ecosystems concentrating the largest share of urban expansion and dry valleys emerging as secondary urbanization nodes. Despite these dynamics, urban land cover accounts for less than 1% of the total regional area, indicating that advanced urbanization can occur with limited direct land conversion but pronounced spatial concentration and uneven ecological impacts. These findings highlight the role of population redistribution and diverse urban trajectories in shaping the environmental consequences of late-stage urbanization.