The gas tax is used to charge motorists and truckers for their use of the public roads, to raise highway revenues, and to encourage motorists and truckers to reduce fuel consumption. However, the federal component of the tax has not been raised in decades. Since 1993, the tax has stayed at 18.4 cents per gallon.
What policymakers have done is aimed to reduce pollution by making adjustments to Corporate Average Fuel Economy Standards (CAFE ), which leads to improved fuel efficiency among cars on the road. But though increased CAFE standards have improved auto fuel efficiency, they’ve also led to declines in gas tax revenues per mile and, along with a fixed gasoline tax, led to shortfalls in the Highway Trust Fund—the fund that pays for roadway maintenance and improvements.