The Central Avenue Line, designated Route C21, C22, C26, C27, C29, is a daily bus route operated by the Washington Metropolitan Area Transit Authority between Addison Road-Seat Pleasant station (C21, C22, C27, C29) or Downtown Largo station (C26) of the Blue and Silver lines of the Washington Metro, and Bowie Park & Ride Lot (C26), Pointer Ridge (C27, C29 Sunday trips), Collington Center (C21, C22), or Bowie State University (C29 Saturday trips).

Routes C21, C22, C26, C27 and C29 operate in central Prince George's County, Maryland connecting riders between Bowie, Kettering, Six Flags America, and Pointer Ridge to the Washington Metro.

All five routes then meet up along the intersection of Central Avenue and Kettering Drive operating parallel to each other.

The route then operates vice versa back to Addison Road station.

These lines connected Capitol Heights, Maryland to Downtown DC and Central Prince Georges County.

But the routes were slowly eliminated or terminated at New Carrollton or Addison Road and replaced by Metrorail after 1978.

Eventually, three lines were created to operate into Central Prince Georges County.

On September 20, 1999, route C26 buses going to Addison Road station in the morning was changed to operate westbound on Lake Arbor Way and turn south into Campus Way North.

C21 and C22 buses also would serve Centre Pointe Office Park on Brightseat Road.

On March 18, 2006, route C29 was extended to serve Bowie State University from the intersection of Northview Drive and Collington Road.

[7] On February 23, 2018, routes C22 and C29 discontinued service along Harry S. Truman Drive south of Mount Lubentia Way due to a long-term construction project.

Customers may board buses at stops along Mount Lubentia Way near Harry S. Truman Drive.

[10] However beginning on March 18, 2020, route C29 was further reduced to operate on its Sunday schedule daily between Addison Road and Pointer Ridge with service to Bowie suspended.

[13] In May 2020, WMATA announced that route C27 will not operate during the 2020 summer season due to the ongoing COVID-19 pandemic and Metro's reduced service since March 16, 2020.