When Robert L. Ehrlich Jr. won election as governor in 2002, he was faced with a tricky problem. He had campaigned on a pledge to build the long-delayed Intercounty Connector in suburban Washington. The highway project would cost a fortune, far more than the state could afford out of its Transportation Trust Fund, and the Republican Ehrlich had taken a hard line against new taxes. He had to come up with some way to pay the $2.6 billion it would eventually cost. The answer? He would make it a toll road. And to give his policies a semblance of geographical...