What does a resilient city look like? A mobility lens on functional reconfiguration

Urban resilience is often assessed through system performance and recovery, yet relatively little attention has been given to how residents experience disruptions through changes in spatial configuration of everyday services. This study conceptualizes resilience as the capacity of urban systems to maintain daily accessibility through feasible alternative configurations of the functional landscape with limited increases in mobility burden. Using U.S. counties as the analytical unit, a Random Forest model with SHAP interpretation reveals that public transit availability, drugstore density, and religious facilities emerge as the most influential determinants of travel distance, followed by road connectivity and other everyday services. The relationship between service density and mobility burden is characterized by clear threshold effect, where initial increases in service density produce substantial reductions in travel distance while additional expansion generates diminishing marginal benefits. Scenario-based perturbation analysis further shows that urban mobility systems exhibit asymmetric resilience responses under service contraction and expansion.