All three of the cities have been pushing hard for approval of the line, which they say will ease traffic congestion and boost business. But for now, the rail line will not include the cities of Anaheim and Orange—both of which have failed to support construction of the $2-billion service, dubbed "CenterLine."

Initial stops on the route approved by the Orange County Transit Authority will include the South Coast Plaza shopping center in Costa Mesa, the mixed-use Irvine Spectrum, John Wayne Airport and the county's Hall of Administration in Santa Ana.

OCTA hopes to begin construction of the rail line in two years, though the project would also require approval of the federal government and other agencies. When completed, the line would carry about 50,000 passengers a day.