Pew has a new set of charts and data on transportation funding in the United States, including this figure which shows that contrary to what you sometimes hear from automotive enthusiasts, it's simply not the case that road tolls, gasoline taxes, and other revenues derived from drivers that pay for America's road infrastructure.
There are large net transfers of financial resources from non-drivers to drivers, especially at the local level (and this ignores the huge implicit subsidy to driving involved in parking regulations), but increasingly at the federal level as well since congress has repeatedly broken the link between gas taxes and road spending. Then to make things especially confusing and unsound, even though gas tax revenue isn't high enough to cover road spending, a healthy slice of gas tax money is diverted away from highways and toward mass transit projects: "Gas tax collections account for more than half of mass transit spending at the federal level and nearly half at the state level."
So driving gets subsidized, which drives down mass transit ridership (and thus fare collections), which we then offset by increasing cross-subsidies to transit. The end result is a lack of cost-effectiveness in both the transit and the highway systems.