The tumbling price of crude oil is helping many Americans save money. It also presents a good opportunity for state governments to raise their gasoline taxes to help pay for road repairs and other needed transportation investments.

Ideally, Congress should raise the national gasoline tax, which has remained at 18.4 cents per gallon since 1993. But federal lawmakers are so fearful of raising taxes just ahead of an election that they refuse to do so. The transportation bill they approved in December provides far too little money to repair and upgrade America’s crumbling transportation system.

That leaves it up to the states to do the job. And now is the time to do it. The average price of gas was $1.99 a gallon in the week ended Jan. 11, down from $2.80 a gallon at the end of June, according to the Energy Information Administration. That decrease gives state lawmakers plenty of room to raise taxes without hitting drivers with a big new expense.

Many states have already acted. Last year, eight states, including Iowa, Michigan and Washington, raised their gasoline taxes, according to the National Conference of State Legislatures. Two others, Kentucky and North Carolina, changed the way that they tax fuel to make sure the revenue they collect does not decline as the price of gasoline fluctuates.