In high-income countries such as the United States (US), coverage rates for vaccination against vaccine-preventable childhood infections remain high. However, the phenomenon of vaccine hesitancy makes maintenance of herd immunity difficult, impeding global disease eradication efforts. Reaching the ‘last mile’ will require early detection of vaccine refusal (due to philosophical or religious choice), identifying pockets of susceptibility created by underimmunization (due to vaccine unavailability, costs, ineligibility), and determining the factors associated with the behaviors to target strategies to ameliorate the concerns. Towards this goal, we harness high-resolution medical claims data to geographically localize vaccine refusal and underimmunization in the US. Our work represents the first large-scale effort for vaccination behavior surveillance and has the potential to aid in the development of targeted public health strategies for optimizing vaccine uptake globally in high-income settings.