A Virginia senator who hated debt insisted the interstates be paid from what drivers put in at the pump. Harry Byrd thought he was imposing discipline, but he built a self-refilling fund that paid ninety cents of every dollar and had no transit counterpart for twenty-seven years. The episode takes the machine apart and shows why it now depends on general-fund transfers.
The lockbox is often overstated: the 1956 restriction was statutory, not constitutional, and the fund's revenue was scheduled to expire in 1972. Whether the gas tax has been unchanged since 1993 depends on a brief dip before 1997. The ninety-ten ratio was a standard, not universal, rate.



