The line was originally called the "Sargent Road Line" as route F5. Route F5 began service in 1978 when Fort Totten station opened providing service between Fort Totten and The Mall at Prince Georges mostly along Sargent Road, East West Highway, and Toledo Terrance during rush hours only.
1993 Service Changes
In 1993, the F5 was renamed the R3 and was extended to Greenbelt station. The new route R3 would operate on the same F5 routing between Fort Totten station and The Mall at Prince Georges, but would also serve the new Prince George's Plaza station and operate along Adelphi Road, Metzerott Road, University Boulevard, Greenbelt Road, Cherrywood Lane to serve Greenbelt station. The R3 would also divert onto 23rd Avenue to serve the Lewisdale neighborhood replacing route R6, divert into the National Archives at College Park along Adelphi Road, and divert into the Beltway Plaza Mall loop in Greenbelt. Weekend service would only operate between Fort Totten and Prince Georges Plaza station. In addition to the changes, route C2 discontinued service to The Mall at Prince Georges with service being replaced by route C4, while route F6 was diverted to New Carrollton station with service being replaced by routes C2 and R3.
2001 Service Changes
On January 13, 2001, route R3 was rerouted along Toledo Terrace and Belcrest Road to serve the apartment complexes behind The Mall at Prince Georges. The line would serve the mall bus bays from Belcrest Road.
2003 Service Changes
Beginning on May 15, 2003, route R3 was permanently rerouted to no longer serve The Mall at Prince Georges due to the Metrobus terminal inside the mall, along with the former G.C. Murphy site the bus used to operate in front of, were demolished to make room for a new Target Store to be constructed on their spots. The R3 remained straight all the way on Belcrest Road until reaching the Prince George's Plaza station which it would enter and serve after making a right turn from Belcrest Road. These changes also affected the 86, C4, F4, F6, F8, R2, R4, TheBus 13, 14, 18, and Shuttle–UM 113.
2007 Service Changes
In early 2007 when the Mosaic Apartments were being constructed and a new roadblock was created on the eastern end of Prince George's Plaza station, the R3 had rerouted along with other routes that served Prince George's Plaza station that formerly made a left onto Belcrest Road. The R3, was required to exit Prince George's Plaza by making a turn onto East-West Highway, then turn Belcrest Road when traveling in the direction of Fort Totten station, or remain straight past Belcrest Road until reaching the intersection of Adelphi Road when traveling in the direction of the Greenbelt station. This change was made as the new road blockand sign by the site of where the Mosaic Apartments were constructed on the eastern end of Prince George's Plaza, which no longer permitted left turns from Prince George's Plaza onto Belcrest Road.
2010 Proposed Changes
In 2010, WMATA proposed to eliminate the R3 completely and replace it with a rerouted F6 which would serve Fort Totten station instead of Silver Spring station. This was due to a reconstructing effort to Metrobus routes in Greenbelt and to cut costs for WMATA. Service inside the Lewisdale neighborhood would be replaced by a rerouted R2 while service inside the National Archives at College Park would be replaced by route C8. Various other routes would have alternative service along the R3 routing. The proposal would be brought up again in 2011 sharing the same proposal idea from the 2010 proposed changes. At the time of the proposal, route R3 operated from 5:30 AM to 9:20 PM on weekdays and 8:05 AM to 7:40 PM on the weekends. The line operates every 30 minutes during weekday peak hours while every 60 minutes all other times.
On June 17, 2012, route R3 was shortened to operate between Greenbelt station and Prince George's Plaza station during the weekday peak hours only with service between Prince Georges Plaza and Fort Totten station being replaced by a rerouted F6 from New Carrollton station which would follow route R3's former routing. Route R2 would operate inside the Lewisdale neighborhood to replace parts of the R3 segment while route C8 diverted into the National Archives at College Park to replace route R3. The R3 would also discontinue the Beltway Plaza loop having it been replaced by the G12, G13, G14, G16 and the R12. The main difference between F6's service between the Prince George's Plaza and Fort Totten stations compared to R3's service between those two stations was that F6 would only operated on weekdays only, while R3 provided service between those two stations daily. The R3 would be renamed from the Greenbelt-Fort Totten Line to the Greenbelt-Prince George's Plaza Line while the F6 would be renamed into the New Carrollton-Fort Totten Line as of a result of the changes.
Proposed Discontinuation
In 2015, WMATA proposed to fully discontinue the R3 once and for all due to low ridership. There would be no alternative Metrobus service along Metzerott Road with the exception of Shuttle–UM. All other parts of the R3 would be served by alternative Metrobus or TheBus service.
Discontinuation Of Service
In March 2016, WMATA announced the discontinuation of R3 service due to low ridership on March 27, 2016. The diversion into the National Archives at College Park was replaced by route C8 while other routes provide alternative service on route R3 former routing. The reason WMATA decided to discontinue R3's service was because of the route's very low productivity and has been an underperformer ever since June 17, 2012. The last day of service of the R3 was March 25, 2016 and the R3 fully discontinued on March 27, 2016 during Metro's round of service changes.
