Cities spent millions on fast gigabit networks. No one is sure what they're good for.

A few dozen cities in America have next-generation broadband networks that offer speeds of 1 gigabit per second — about 50 times faster than a typical connection. These super-fast connections were supposed to revolutionize Americans’ experience of the Internet and rev up the country’s noncompetitive broadband market. When these networks were being built, advocates pointed to a number of potential applications.

Gigabit networks, they promised, would enable users to interact in complex virtual reality environments. They’d make possible good-as-life teleconferencing that could allow seniors to visit doctors from home. But six years after the first super-fast connections went live, even proponents concede no “killer” gigabit application has emerged. Most of their potential, critics say, is simply ignored by users. And building gigabit networks nationwide would be a colossally expensive undertaking. That has caused even some former enthusiasts of these networks to wonder whether the early hype around gigabit networks was misplaced. Perhaps it makes sense to settle for more incremental — and much less expensive — upgrades to the networks we already have.