U.S. Transportation Secretary Ray LaHood says the route is now part of the California rail corridor, a technical designation that endorses the viability of high-speed train travel in the region.
Officials say the designation also signals a possible future collaboration between California's proposed high-speed rail system and a separate project shuttling passengers between the two regions.
LaHood, U.S. Sen. Harry Reid and California Department of Transportation Director Will Kempton made the announcement in Las Vegas on Thursday.
Reid used the event to repeat his support for the DesertXpress train project. The electric train would run between Las Vegas and Victorville, Calif., at up to 150 mph.