The federal government and many states are seeing shortfalls in their transportation budgets in part because the gasoline taxes they use to generate those funds are poorly designed. Thirty-two states and the federal government levy “fixed-rate” gas taxes where the tax rate does not change even as the cost of infrastructure materials inevitably increases over time. The federal government’s 18.4 cent gas tax, for example, has not increased in over twenty years. And almost half the states (24) have gone a decade or more without a gas tax increase.