You might notice roads and bridges in need of repair as you drive around this holiday weekend. But revenue from a key funding source, the gas tax, has been declining. It's charged per gallon of gas purchased. U of I professor Don Fullerton says it was created on a simple concept:
"The more you drive, the more gas you use. The more you ought to have to pay for the road. It's sort of a benefit principle of taxation."
Improved mileage in vehicles means less gas is being used. Fullerton says change is needed to keep up with demand: