The Regional Transportation District (RTD) is the public transit agency for Denver and its metropolitan area in the U.S. state of Colorado. It operates a large bus and rail system that comprises 10 rail lines—both light rail and commuter rail—and 102 bus routes. RTD's rail system consists of 6 light rail lines and an additional 4 commuter rail lines with 84 stations and of track. The bus network consists of 85 local routes, 12 regional routes, 10 limited routes, and 5 express routes to Denver International Airport. In , the entire system had a ridership of , or about per weekday as of , making RTD the largest transit agency in the Mountain states by both ridership and the number of routes.
RTD serves a area with a total of 3.09million people in 40 municipalities and 8 counties. The agency was organized in 1969 and is governed by a 15-member board of directors that is elected from districts within the service area. RTD has a budget of $1.5billion for fiscal year 2026 with a majority of its revenue derived from a 1percent sales tax. The agency has a fleet of 955 fully accessible buses; some of the buses are operated by private carriers under contract with RTD. The rail system comprises 267 railcars, including 201 high-floor light rail vehicles.
Several existing bus operators were acquired and consolidated into RTD to form the initial bus system, later named "The Ride", that debuted on April 12, 1974. A personal rapid transit system had been studied but was scrapped in favor of a conventional light rail system, which was approved by voters in 1987. The first section of the light rail system opened on October 8, 1994, between Downtown Denver and I-25 & Broadway station. The FasTracks transit plan was approved in 2004 and funded the rapid expansion of the RTD system to encompass of new commuter rail and light rail, of bus rapid transit (BRT) service, and enhanced bus service.
History
Bus Bus service in Denver dates back to 1924, when Denver Tramway began the first bus between Englewood and Fort Logan. Buses had completely replaced the previously expansive streetcar system in metro Denver by 1950, and the privately owned Denver Tramway served the City and County of Denver, as well as older portions of Arvada, Aurora, Englewood, Golden, Lakewood, Westminster, and Wheat Ridge and smaller suburbs. In 1969, the Colorado General Assembly created the RTD to provide public transportation to five additional counties in the metropolitan area.
Denver Tramway Company continued its service under sponsorship of the City and County of Denver until April 18, 1971, when it was taken over by Denver Metro Transit, an entity created by the City and County of Denver. Suburban services only continued for those suburbs willing to contribute a subsidy. It acquired privately owned companies, improved service frequency, and expanded to routes that commercial carriers previously operated such as airport buses.
By 1972, RTD had created a plan for a personal rapid transit (PRT) system in the area, which included of elevated PRT and extensive bus service throughout the areas served by RTD. The PRT system would have 58 stations and a fleet of 800 electric vehicles that could each carry 12 passengers and travel at up to . Later that year, the Urban Mass Transportation Administration (UMTA) selected RTD to develop PRT as a demonstration project. In 1973, residents voted for a sales tax of 0.5% over the six counties served by RTD for ten years; 20% of the funds would be used for expanded bus services and the other 80% was earmarked for PRT construction, although that project was later scrapped. The tax became effective January 1, 1974, and was raised to 0.6% on May 1, 1983. On January 1, 2005, the tax rate increased to 1.0%.
In 1973, RTD started operating a demonstration bus service, the Parker Stage, between Downtown Denver and the suburb of Parker.
In February 1974, RTD began operating express services between Denver and various points in the metropolitan area, using 25 buses the agency had leased the previous month. RTD later acquired and consolidated the local bus systems. Evergreen Transit, which primarily ran commuter bus service between Evergreen and Denver, was the first, and RTD started running service on April 12, 1974. Denver Metro Transit became part of RTD in July 1974. RTD acquired the bus system in Boulder from the Public Service Company of Colorado. Other RTD acquisitions included Longmont Mini, the Englewood-Littleton-Ft. Logan service, Public Service and Northglenn Suburban Service. RTD also acquired the privately owned Denver-Boulder Bus Company, which ran airport buses.
RTD expanded and improved service frequency in the mid-1970s, and its services were expanded to routes that commercial carriers previously operated, although inflation prompted RTD to implement a new fare structure in February 1978. On September 11, 1978, RTD completely replaced all bus routes, formerly mostly radials from downtown Denver following old streetcar routes, with new routes based on a grid system, numbered based on the hundred blocks of the street grid. For instance, the new Colorado Blvd (4000 east block) route was number 40, and the new 10th Avenue (1000 north block) route was number 10. RTD reached a record number of weekday passengers in 1980, the same year it expanded the Park-n-Ride system and acquired 216 new buses, 89 of which were articulated. RTD also made its service more accessible to elderly and handicapped people.
In 1979, federal approval was granted for the 16th Street Mall in downtown Denver, originally known as Transitway. The project allowed express bus productivity to double and was eventually intersected by RTD's first light rail line, the D Line, at Stout and California streets. Construction began in 1980.
State law required privatization of 20% of bus lines in 1989, with this quota increased to 35% in 2002. In September 1994 Downtown Express/High Occupancy Vehicle (HOV) lanes were opened to buses, and to carpools a year later.
RTD's Market Street Station closed on May 11 and 12, 2014 and was replaced by the newer Union Station. The Free MetroRide service began along 18th and 19th streets between Union Station and Civic Center Station.
Light rail RTD began planning for a light rail in the mid-1980s, after the successful opening of the San Diego Trolley in 1981 and amid a surge in light rail construction in mid-sized cities nationwide (Buffalo, Portland, Sacramento, and San Jose also built systems at the same time).
RTD's first line, the Central Corridor between the 30th & Downing and the I-25 & Broadway stations (now part of the D Line and L Line) opened on Friday, October 7, 1994. It operated with free service for that first weekend, with revenue service starting on October 10. More than 200,000 passengers rode the new system during its opening weekend, when the fleet comprised only 11 Siemens SD-100 rail cars.
The Southwest Corridor light rail extension to Mineral Avenue in Littleton opened in July 2000, followed by the Central Platte Valley spur to Denver Union Station in April 2002. In 2003, the downtown portion of the original line between Speer Boulevard and 14th Street was realigned as a result of construction of the Colorado Convention Center.
In April 2006, transit workers of the Amalgamated Transit Union went on strike for the first time in 24 years, citing increased health care costs, mandatory overtime, and disproportionate wage increases relative to upper management. Workers walked off on April 3, shutting down the light rail system and decreasing bus service to about 45% of its normal capacity. A revised contract was approved by the union on April 7, and service resumed on April 10. The strike lasted seven days, and although thousands of commuters were stranded by the strike, only a few backups were reported as customers made makeshift arrangements for commuting or waited out the strike.
The Southeast Corridor, a component of the Transportation Expansion Project, opened on November 17, 2006, along I-25 to Lone Tree and a branch along I-225 to Parker Road. The West Rail Line opened on April 26, 2013. By April 2013, the system had expanded to 170 light rail vehicles, serving of track.
The light rail R Line to Aurora and Lone Tree opened on February 24, 2017.
RTD made significant service changes and suspended service on multiple bus and light rail lines due to the COVID-19 pandemic. The F Line was suspended on September 20, 2020, and the C Line was suspended on January 10, 2021, with both routes being permanently discontinued in January 2023.
Commuter rail With the voter approval of FasTracks in 2004, RTD began planning for a series of commuter rail lines. The first of which, the A Line servicing Denver International Airport, opened on April 22, 2016. The second, the first 6.2 mile segment of the B Line, officially opened on July 25, 2016.
As one of the first new commuter rail systems in the country planned after enactment of the Rail Safety Improvement Act of 2008, positive train control (PTC) and vehicle monitoring system technologies are implemented along the system's commuter train lines. After the A Line opened between Denver Union Station and Denver International Airport, it experienced a series of issues related to having to adjust the length of unpowered gaps between different overhead power sections, direct lightning strikes, snagging wires, and crossing signals behaving unexpectedly. In response, Denver Transit Partners, the contractor building and operating the A Line, stationed crossing guards at each place where the A line crosses local streets at grade while it continued to explore software revisions and other fixes to address the underlying issues. The Federal Railroad Administration allowed RTD to open its B Line as originally scheduled on July 25, 2016, because the B Line only has one at-grade crossing along its current route that is not designated to be a quiet zone. However, FRA previously halted testing on the longer G Line to Wheat Ridge – originally scheduled to open in late 2016 – until more progress could be shown resolving the A Line crossing issues. On April 26, 2019, the G Line opened to the public.
Bus rapid transit
In January 2016, RTD opened the first branded BRT line in the Denver metropolitan area, the Flatiron Flyer. It travels along the U.S. Route 36 corridor between Boulder and Denver, with some service continuing to Aurora, and uses freeway stations for faster access. The Flatiron Flyer expanded to seven routes, but two were suspended during the COVID-19 pandemic and not subsequently restored. A feasibility study into further BRT expansion was completed in 2019 by RTD and recommended the construction of eight corridors by 2050.
The Colfax Avenue corridor in Denver was chosen for a new BRT system, named LYNX, and began construction in October 2024 under the Denver Department of Transportation and Infrastructure. The BRT line will have 28 stations and covers of the corridor between Union Station and Colfax station in Aurora near Interstate 225. A within Denver uses center-running bus lanes, while other sections are in mixed traffic. LYNX is planned to enter service by the end of 2027 with service every four minutes during weekdays, seven minutes on weekdays, and fifteen minutes at night.
Accidents and incidents On January 28, 2019, an R Line light rail train derailed the junction of East Exposition Avenue and South Sable Boulevard (between Aurora Metro Center and Florida stations) due to excessive speed. The curve has a speed limit of but the train approached at . One woman's foot was amputated by the train wheels after she was ejected from the car during the accident, eight other passengers were also injured. Although determined responsible for the accident, no charges were filed against the driver.