Public support for the projects has overcome some concerns about costs, as the U.S. plays catchup with other parts of the world that have built extensive high-speed networks.

The Department of Transportation announced more than $6 billion in grant funding for high-speed rail projects this week. The money comes amid ongoing support for a technology that has also encountered concerns about its costs.

Brightline West, an affiliate of Florida’s Brightline intercity rail service, was awarded $3 billion in federal funds for its proposed line between Las Vegas and Los Angeles, which would zoom passengers between the cities in two hours.

The California High-Speed-Rail Authority was awarded $3.1 billion to continue work on its system, which will ultimately connect Los Angeles and San Francisco in less than three hours.

Definitions of high-speed rail vary, but it typically refers to passenger trains that travel at least 125 mph and can reach more than 220 mph.