The proximity–access paradox in Medicaid administrative services: Transportation barriers and spatial inequalities in the United States

Health equity depends not only on insurance eligibility, but also on access to the administrative system that enables coverage. Using Medicaid administrative offices in the United States as a case, we assess accessibility from over 80,000 census tracts to the nearest Medicaid office across driving, public transit, bicycling, and walking using distances and travel times. We identify a proximity–access paradox: while geographic distances to offices are broadly similar across modes, functional accessibility diverges sharply once translated into time and transportation feasibility. Driving times are generally short and consistently feasible, whereas walking and transit often require substantially longer times, and public transit is infeasible for over 40% of tracts. Multilevel analyses further show that accessibility varies systematically with neighborhood income, racial composition, age structure, disability prevalence, and state context. These findings highlight transportation barriers as an important structural determinant of administrative access to health insurance coverage and suggest that improving health equity requires policy attention not only to eligibility and coverage expansion but also to the transportation systems that enable people to reach the administrative institutions of health systems.