The dream: Super fast trains use magnets to float inches off a track and hit speeds of 300 miles per hour, whisking travelers between cities in record time.

The reality: Train that runs on magnetic levitation technology -- or maglev -- are expensive to build, and so far, only cover short distances. But they're picking up steam. China has one that's a bit slower and only goes from the Shanghai airport to just outside the city. Japan recently approved construction of one that's expected to be in operation by 2027. Experts expect more of these trains in Asia in the coming decades.

In the United States one private group is trying to build a maglev train from New York to Washington, D.C., which would make the trip in an hour. It's an expensive and time consuming endeavor, so the group is starting small -- aiming to complete a 38-mile stretch between Baltimore and D.C. sometime in the next 10 years.

But some experts are skeptical that even this small line will ever get built.