The state of Washington could consider an 11.5-cent increase to the gas tax as a way to pay for transportation projects across the state. But, there is growing concern that a tax at the pump is not the best revenue source. That's why Oregon, for example, is experimenting with a pilot project that charges driver per mile; miles are tracked either with GPS or with an odometer check. We want to know what you think: would you rather pay a tax when you pump or pay per mile driven?