The American Public Transportation Association told CNN that a nationwide surge in mass transit riders has its member agencies scrambling to meet the new demand.

"Once people get a chance to try public transit and they find it works for them, they stick with it," said Cynthia Stabb of Tulsa Transit. "We believe the demand is here to stay."

CNN noted that while high fuel costs increase ridership, fuel costs are also going up for buses. And with many transit agencies depending on sales tax revenues for their funding, an economic slowdown squeezes their budgets at a time when they should be spending more.

I have real concerns about our ability to sustain services and maintain infrastructure," said Cal Marsella, the head of the Denver transit system.