Oregon is doing exactly this, apparently. The Economist had an interesting article on it recently. http://www.economist.com/news/united-states/21588097-oregon

Oregon is doing exactly this, apparently. The Economist had an interesting article on it recently. http://www.economist.com/news/united-states/21588097-oregon-wants-tax-motorists-miles-driven-not-petrol-burned-will-it-work-roads-less http://www.economist.com/news/united-states/21588097-oregon-... It does seem like raising the gas tax would be an easier option.