Although intended to support U.S. highways and mass transit, revenue on a per-gallon tax on motor fuels, imposed at refineries and passed on to consumers, is insufficient to sustain the U.S. transportation network. One view is that Congress should not only renew the tax levy that is set to retire September 30 but should also overhaul the method for collecting it to ensure adequate revenue is raised for the future. Americans have been buying fewer gallons of gas since 2008 and paying less in taxes. Increasing the tax in stages will cushion the effect on consumers. Rather than being tied to the number of gallons purchased, it should be levied as a percentage of the value of the gasoline purchased.