New road construction costs on average $1mill per lane mile.(more for concrete, and that lasts around 40-50 years in low traffic situations) So a 4 lane road costs around $4mill per mile. Not including shoulders and median work. Asphalt roads last around 20 years if constructed correctly. (Most are constructed for far lower traffic than they see now, as they are built to old standards) To fix a road isn't cheap either, and will add up to the cost of new construction very quickly. NC has (as was stated in another comment) the most lane-miles of any state, and a relatively low population. They have to sharge more taxes on each gallon of gas sold to make up for that, if all of their money is coming from gas-taxes. You know all of those "Clickit or ticket" signs you see? Those are ransom notes from the Feds. You will enforce this law, or you get no money for your infrastructure.