“States are allotting a growing share of the funds they raise from gas taxes to debt service and spending unrelated to roads and bridges, making them more reliant on federal assistance to pay for new infrastructure. The shrinking pot of state cash is one reason why governors increasingly are in a panic over a congressional impasse about replenishing the federal Highway Trust Fund. The federal fund, too, is running out of money and will cut disbursements to states if Congress doesn’t intervene. Compounding the problem, gas-tax revenue has come in below targets in many states, in part because of a rising use of fuel-efficient cars and weaker-than-expected economic growth.”
http://online.wsj.com/articles/states-siphon-gas-tax-for-other-uses-1405558382