Fourteen of the Trolley system's stations operate as transfer stations, which allow passengers to transfer between lines. There are two universal transfer points (i.e., allowing transfers among all four lines) in the system in downtown San Diego: the 12th & Imperial Transit Center station, and the America Plaza/Santa Fe Depot stations. Six Trolley stations are end-of-line stations. Of the 53 San Diego Trolley stations, 37 stations are within the city limits of San Diego, serving various neighborhoods in San Diego; the other 16 stations are located in the cities of Chula Vista, El Cajon, La Mesa, Lemon Grove, National City, and Santee.