The internal rate of return to public investment in agricultural R&D is estimated for each of the continental U.S. states. Theoretically, our contribution provides a way of obtaining the returns to a local public good using Rothbart’s concept of virtual prices. Empirically, we use the spatial dependency among states generated by knowledge spillovers to define the ‘appropriate’ jurisdiction. We estimate an average own-state rate of 17% and a social rate of 27%. These figures should inform the policy debate on the allocation of federal funds to research in anticipation of a possible global food crisis.