Louisiana has the sixth oldest gasoline tax in the nation, according to a survey by the National Conference of State Legislatures.

Only Alaska, Oklahoma, Mississippi, South Carolina and Tennessee have had their gasoline assessments on the books longer than Louisiana, which is 26.1 years.

The issue is relevant because an 18-member panel named by Gov. John Bel Edwards is studying the gas tax as a key source of dollars in any push to trim the state's $12.7 billion backlog of road and bridge needs.

Motorists pay 38.4 cents per gallon in state and federal taxes, including 20 cents in state charges.

Efforts to boost the state gas tax have died for years, mostly because of resistance to tax hikes.

However, the fact the governor is behind the current study, as is a wide-range of legislative and business leadership, means this one may result in sweeping legislation for the 2017 legislative session.

The NCSL review said 18 states and the District of Columbia raised their gas taxes or adjusted formulas used to charge motorists between 2013-15.

Last year Georgia raised its gasoline tax from 7.5 cents per gallon to 26 cents.

Louisiana is one of 15 states that has not changed its gas tax in two decades or more.

The federal rate has not changed in 22 years.

Shawn Wilson, secretary for the state Department of Transportation and Development and co-chair of the review panel, said last week flooding in south Louisiana may have an impact on what the committee recommends.

State road and bridge damage is up to $25 million, and thousands of residents lost homes during record rain and flooding that began Aug. 11.

Louisiana and other states are heavily dependent on federal aid for transportation improvements.

"The federal role in highway spending is expected to get smaller because fuel tax revenues are decreasing and Congress is holding off on raising the federal gas tax rate," according to a report by George Mason University.

Follow Will Sentell on Twitter, @WillSentell.