A 21-minute trip from Houston to San Antonio is a few miles closer to reality. A proposed project that would connect Austin, Dallas, Houston, Laredo, and San Antonio via a futuristic pod-and-tube system is now one of four U.S. finalists in a global transportation contest.

Once in San Antonio, getting to Austin would take another eight minutes for Houston travelers. The trip from Houston to Dallas, not including the time for layovers, would take 48 minutes.

Hyperloop One, the company behind this transportation innovation, has designated the envisioned 640-mile, five-city Texas Triangle system as a finalist. The three other U.S. finalists in the Hyperloop One Global Challenge are:

• A 488-mile system linking Chicago; Columbus, Ohio; and Pittsburgh
• A 360-mile system linking Cheyenne, Wyoming; Denver; and Pueblo, Colorado
• A 257-mile system linking Miami and Orlando

The brains behind the proposed Texas Triangle project say hyperloop passenger pods would reach speeds of up to 700 mph.

The north-south leg of the Hyperloop system in Texas would run from Dallas to Laredo, while the east-west leg would operate between San Antonio and Houston.

“Hyperloop One will now work closely with each winning team to validate and analyze their proposals further, and provide initial ridership forecasts, business case, and preliminary technical analysis of the route and corridor, tailored to the needs of the individual route,” the company says in a release.

In May 2016, Hyperloop One invited innovators, universities, businesses, and government agencies to develop regional proposals for a Hyperloop system. Hyperloop says the 10 global finalists were picked based on whether a project had well-defined routes and implementation strategies, significant stakeholder involvement, a “compelling” business case, and an “innovative and creative” approach to building a Hyperloop system.

Here is Hyperloop’s description of how one of its systems will work:

“With Hyperloop One, passengers and cargo are loaded into a pod, and accelerate gradually via electric propulsion through a low-pressure tube. The pod quickly lifts above the track using magnetic levitation and glides at airline speeds for long distances due to ultra-low aerodynamic drag.”

This summer, Hyperloop successfully carried out a test in Nevada of its concept. Hyperloop expects to have three full-scale systems up and running by 2021.

Shervin Pishevar, co-founder and executive chairman of Hyperloop, says the Hyperloop One Global Challenge “became a movement of thousands of people from more than 100 countries over six continents. Like us, they believe that Hyperloop will not only solve transportation and urban development challenges within communities, it will unlock vast economic potential and transform how our cities operate and how we live.”

Tesla and SpaceX legend Elon Musk first floated the Hyperloop concept in 2013.