States primarily link transportation tax revenues to fossil fuels and number of vehicles and drivers. Transition to autonomous vehicles (AV) is likely to significantly erode each of these tax bases. Simulations for six states suggest they could lose between 2 and 9.2 percent of total tax revenues and 60 percent or more of transportation tax revenues once AVs are fully adopted. States have the opportunity to tax mobility more broadly before the population transitions to AVs. Reform options include imposing the sales tax on all mobility services, levying a VMT tax, or imposing congestion charges.