San Diego Trolley opened in 1981 with of operations on the South Line. Additional vehicles were purchased in 1983, and the South Line was mostly double-tracked by 1984, largely on the strength of demand for more frequent headways. The business plan's incremental building and funding approach was vindicated. The East Line opened to Euclid Avenue in 1986, and was extended to El Cajon in 1989 and Santee in 1995. Service was extended northward to Old Town in 1996 and then eastward in Mission Valley in both 1997 and 2005.