With a full-scale hyperloop system testing in the Nevada desert, Hyperloop One is moving forward with plans to build Elon Musk’s vision for high-speed tubular transportation.

One of the questions is where, and the downtown Los Angeles startup has narrowed the field from hundreds of applicants to 10 candidates from five countries through its Hyperloop One Global Challenge.

Combined, the winning routes span 4,121 miles, connecting 53 urban centers and nearly 150 million people in the U.S., Canada,…