Though some older segments of the network — notably the Pennsylvania and New Jersey turnpikes and Interstate 95 in Maryland and Virginia — are toll roads, most of the 46,876-mile system has been toll-free.

“We believe that this is an area where the states have to make their own decisions,” said Transportation Secretary Anthony Foxx. “We want to open the aperture, if you will, to allow more states to choose to make broader use of tolling, to have that option available.”

The question of how to pay to repair roadways and transit systems built in the heady era of post-World War II expansion is demanding center stage this spring, with projections that traditional funding can no longer meet the need…

“The proposal comes at the crucial moment for transportation in the last several years,” Foxx said. “As soon as August, the Highway Trust Fund could run dry. States are already canceling or delaying projects because of the uncertainty.”