Sun Tran is the public transit system serving the city of Tucson, Arizona. In , the system had rides, or about per weekday as of . 100% of the fleet utilizes clean-burning fuels, such as compressed natural gas (CNG), biodiesel, and hybrid technologies. In addition to more than 40 bus routes, the system also includes the Sun Link modern streetcar line. History According to David Leighton, historian for the Arizona Daily Star newspaper, Sun Tran's history began in 1897 with the organization of the Tucson Street Railway, which by the following year was providing Tucsonans with regular mule-powered streetcar service. Streetcar tracks existed in parts of present-day downtown and to the University of Arizona. Within a few years, lack of profit caused the company to be sold and it was reorganized as Tucson Rapid Transit Co. (TRT). It shortly came under common ownership with Tucson Gas, Electric Light and Power Co. By 1906, mules were replaced by electricity as the driving force behind the streetcars in Tucson. Four years later, TRT published its intent to increase the amount of track for its electric cars but insufficient money prevented this from occurring. In 1910, TRT owner United States Light and Traction was acquired by the newly formed Federal Light and Traction. In October 1925, Tucson Rapid Transit Co., having realized that buses were more flexible and economical to run than streetcars and were the future of public transportation in the Old Pueblo, bought the White Star Bus Line. This small bus company would become the basis for TRT's bus service in town. Also around the same time, Roy Laos Sr., noting the lack of transit service to the south and west sides of town founded the Occidental Bus Line to serve these areas. Laos' bus service would later be called Old Pueblo Transit. In 1930, control of Federal Light and Traction was acquired by Cities Service. On January 1, 1931, Tucson Rapid Transit formally ended all electric streetcar service in town. From this day forward it became strictly a bus company. Five years later, Jacob M. Bingham established the Mountain View Bus Line with one bus. His goal was to provide service to outlying areas that TRT didn't serve but turning a profit or even just paying his bills was difficult and soon enough TRT bought his small enterprise. During World War II, ridership increased to a large degree, in part