With Kansans driving less and using more fuel-efficient vehicles, the state is studying the possible impact of a drop in fuel tax revenue.

The Kansas Department of Transportation says the decline in revenue from motor fuel taxes is a concern because that money is the primary way the state funds its highway projects.

The Wichita Eagle reports Kansans drove 82.2 million miles each day last year. That’s an increase from 81.9 million miles in 2010, but a drop from 83 million in 2006.

Leif Holliday, a traffic engineer for the transportation department, said traffic had grown 1 to 3 percent annually until 2007, when it dropped to levels seen five to eight years before.

KDOT spokeswoman Sally Lunsford says most states are collecting declining motor fuel tax revenue.