The Silver Line offers frequent, all-stops service along the El Monte Busway and the Harbor Transitway, which until the opening of this Metro Liner route on December 13, 2009 had been mostly served by peak-hour express buses. Silver Line buses make a limited amount of stops in Downtown LA (10 per direction), all located near Metro Rail stations, major employment centers and tourist destinations.
Operation of the Silver Line is partly funded by the Metro ExpressLanes project that converted the El Monte Busway and the Harbor Transitway into high-occupancy toll lanes that allow solo drivers to pay a toll to use lanes that are otherwise reserved for buses and vehicles with 2, 3 or more occupants. The Metro ExpressLanes project has also provided funding to improve amenities at the station stops along the line.