Regional Transportation District

The Regional Transportation District, more commonly referred to as RTD, is the regional agency operating public transit services in all or a portion of eight counties (six of the ten counties in the Denver-Aurora-Centennial, CO Metropolitan Statistical Area, plus Boulder County and Weld County, but not Elbert County, Park County, Clear Creek County, or Gilpin County) in the U.S. state of Colorado. It operates over a 2,342-square-mile (6,070 km²) area, serving 3.08 million people. RTD was organized in 1969 and is governed by a 15-member, publicly elected Board of Directors. Directors are elected to a four-year term and represent a specific district of about 180,000 constituents.

RTD currently operates a bus and rail system consisting of 10 rail lines and 126 bus routes throughout the Denver region. RTD's bus network consists of 86 local, 23 regional, 14 limited, and 3 SkyRide bus routes plus some special services. The rail system consists of 6 light rail lines and an additional 4 commuter rail lines with 77 stations and 113.1 miles (182.0 km) of track.

In 2025, the system had a ridership of 64,192,300, or about 257,300 per weekday as of the fourth quarter of 2025, making RTD the largest transit agency in the Mountain West region by both ridership and the number of routes.

Initially a bus-only system, RTD began operating light rail service in 1994 when the first segment of track opened through Central Denver. Following additional extensions into the Southwest and Southeast Corridors in the early-to-mid 2000s, the RTD rail network began to expand rapidly following the 2004 voter-approved FasTracks transit expansion plan. Once complete, FasTracks will have added 122 miles (196 km) of new commuter rail and light rail, 18 miles (29 km) of bus rapid transit (BRT) service, and enhanced bus service across the eight-county district.