States consider switching from fuel taxes to mileage-based charges.

As fuel taxes generate less revenue each year due to fuel efficiency and the rise of electric cars, U.S. states are experimenting with road usage charging programs aimed at replacing motor fuel taxes. Only three states are currently generating revenue from road usage charges, despite the looming threat of an ever-widening gap between states’ gas tax proceeds and their transportation budgets. Many states have implemented stopgap measures, but road usage charges are attracting the bulk of the academic attention, research dollars and legislative activity. However, there are still hurdles to overcome, including public acceptance and concerns about social and environmental implications.