In San Diego, the San Diego Trolley's Blue Line goes from the San Ysidro Border Crossing, roughly along Interstate 5 to Downtown and Old Town. As the trolley travels it also serves as a means of transportation for the southern suburbs. Passengers may transfer at the 12th & Imperial station to an Orange Line trolley, serving the eastern suburbs. Another option is to transfer at the Old Town Trolley Station to a Green Line trolley serving Mission Valley and the campus of San Diego State University.