In July 2005, San Diego, California, Trolley officials and riders celebrated completion of the light rail system's eighth extension. The 6-mi (9.7-km) Mission Valley East project closed the gap in the 53-mi (85.3-km) system and provided service to San Diego State University (SDSU). The project allowed for the introduction of the 19-mi (30.6-km) Green Line, which operates between Old Town and Santee on existing, new, and shared tracks. The Green Line is distinctive in a number of ways. It is a nonradial corridor that does not serve downtown San Diego. It directly serves the 35,000-student SDSU campus and surrounding community through the system's first tunnel and underground station. In addition, the line links a variety of regional activity centers along Mission Valley's intense residential and employment corridor. In fall 2005, the Metropolitan Transit System and the San Diego Association of Governments conducted two surveys and a passenger count to help understand more about who rides the Green Line, why they ride it, and where they are going. Survey results indicate that the Green Line has changed the composition and riding habits of transit users, resulting in high proportions of school trips, increased frequency of transit use, high numbers of choice riders, and high percentages of prepaid fare use. The Green Line has increased transit trips at SDSU by over 350%. The surveys also prompted plans for improvements, including operating later night service, pursuing station modifications that would allow the Green Line to extend into downtown, and considering partnerships with SDSU to expand the college semester pass program.