The Sacramento Regional Transit District, commonly referred to as SacRT (or simply RT), is the agency responsible for public transportation in the Sacramento, California area. It was established on April 1, 1973, as a result of the acquisition of the Sacramento Transit Authority. In addition to operating over 81 bus routes with connecting bus service in the Sacramento area covering , SacRT also operates a large light rail system, which ranks currently as the sixteenth busiest light rail system in the United States. In , the system had a ridership of , or about per weekday as of . In addition to the city of Sacramento, SacRT serves Sacramento International Airport, much of the northern portion of Sacramento County which includes the incorporated cities of Citrus Heights, Folsom and Rancho Cordova. The unincorporated areas of Sacramento County under the SacRT service area include Arden Arcade, Carmichael, Fair Oaks, Florin, Gold River, North Highlands, Orangevale, Rio Linda and Rosemont. The system formerly provided express bus service between Downtown Sacramento and Elk Grove until the mid-2000s when that city took over bus operations under the newly created e-tran; SacRT now operates e-tran as a contractor to the City of Elk Grove after signing a five-year contract to operate its service in June 2019, replacing MV Transportation. It also provided contracted bus service to neighboring Yolo County (covering West Sacramento, Davis and Woodland); those routes and operations were later taken over by Yolobus after its formation on January 3, 1982. Yolobus have retained the RT assigned route numbers for their routes as they continue to service Downtown Sacramento and e-tran has since revised its route numbering scheme when they completed their comprehensive operational analysis in 2018. Services Transit bus The RT system operates 67 bus routes, as of 2013, with service between 5:00 a.m. and 11:00 p.m. daily, and ending much earlier on weekends. Frequencies range between every 15 and 80 minutes (some express buses run only a few times a day). There has been proposals in the past to expand the service hours to late nights to accommodate passengers, businesses and communities, but have been slow to implement these ideas. The most recent changes were announced in August 2012, and is gradually making plans to improve and expand bus services system-wide by 2017. Since light rail has opened, buses have generally acted as feeders to light rail routes. Airport Express SacRT has