Motorists are hitting the roads in greater numbers than they ever have. The latest Federal Highway Administration (FHWA) data show the number of vehicle miles traveled in the United States has finally rebounded, reaching an all-time high of three trillion miles driven in the past twelve months and surpassing the pre-recession peak of 2007.

When economic turmoil struck, drivers responded to the rise in unemployment and lack of economic growth by putting down the car keys. Slowly, they have picked them back up, and this year, overall travel is up 3.4 percent. The return has taken government officials by surprise. As late as last year, US Department of Transportation economists expressed amazement that the vehicle miles traveled had not rebounded earlier as the economic recovery kicked in.

Officials have cited the decline in miles traveled to call for an expansion in tolling to fill in for "falling" gas tax revenue. US Senate Commerce, Science and Transportation Committee Chairman John Thune (R-South Dakota) on Tuesday called for passage of the federal highway funding bill, the Drive Act, that includes a number of provisions promoting the use of toll roads.

"While transportation bills are nothing new here in the Senate, the bill before us today is notable because it's the first transportation bill in almost a decade to provide more than two years of funding for our nation's infrastructure needs," Thune said.

The massive highway and transit program funding bill would ease the process by which states create a "pilot project" to convert an existing interstate freeway into a toll road, to the applause of industry groups such as the US Tolling Coalition. By contrast, groups representing regular road users such as the National Motorists Association, American Trucking Association, Farm Bureau, FedEx and UPS blasted the idea.

"Pilot programs exist to gauge the viability of an idea, and the Interstate System Reconstruction and Rehabilitation Pilot Program has proven that tolling existing interstates is not a feasible option," the groups wrote in joint a letter to Senate lawmakers. "It should be repealed, not expanded."

Overall, gas tax revenue is not falling nationwide. According to the US Census Bureau's latest figures, combined state and local gasoline tax revenue was $41,447,220 in 2012, a record high. Even during the recession, gas tax receipts dipped only once, by 2.9 percent in 2009. Gas tax revenue has increased every year since. Federal gas tax receipts recovered from the 2007 peak of $24.5 billion, reaching $25 billion in 2012. While the Census Bureau has not released more recent numbers, they increase with vehicle miles traveled.