McLean–Crystal City Line

In 2010 during WMATA's FY2011 budget, WMATA proposed to eliminate route 23C and replace it with route 23A.[7] This was due to bus transfer being restricted at Langley, as riders will have to stop at Old Dominion Drive and Chain Bridge Road to transfer to the 15K or 15L of the Chain Bridge Road Line.

With the 23C being proposed to be converted to the 23A, service at Douglas Park, which operates via Walter Reed Drive and Arlington Mill Drive, would be discontinued.[7] Arlington Transit route 77 will continue to provide service on Douglas Park, following the same path as the 23C, although ART 77 will split on South Glebe Road to continue straight towards Court House station.

In 2013, WMATA proposed to reconstruct the 23 line, by revising the 23A and add a new route, the 23T.[8] The 23A will be rerouted to operate via Dolley Madison Boulevard instead of Chain Bridge Road, to serve Salona Village Shopping Center at McLean. With the new Silver Line service planned to open in 2014, the 23A will serve McLean station and Tysons Corner station, however, it will now terminate at Tysons Corner Shopping Center, no longer serving Tysons-Westpark Transit Station via Tysons Galleria. Since route 23C was still in service during the proposal, it was omitted from the reconstructive plan for the 23 line. Although the 15K and 15L was still mentioned as an alternate route for Langley, as both routes operates via Chain Bridge Road where the 23A will no longer operate, the 23C is most likely being proposed to be eliminated.

The reason why WMATA planned these changes was to clear up bus bunching with Fairfax Connector on Chain Bridge Road, as those routes operates nearly the same path as the 23A.[8]

To make way for the Silver Line, the 23A was truncated from Tysons-Westpark Transit Station to Tysons Corner Center March 30, 2014.[5] 23B & 23T were introduced March 30, 2014 replacing the 23C. Alternate service to Langley is provided by routes 15K and 15L at the neighborhood of McLean. A temporary 23W was added to serve as a shuttle bus between Tysons-Westpark Transit Station and Tysons Corner Center, until the Silver line opens. The 23W runs under the Westpark Shuttle Line.

Starting on June 26, 2016, weekday middays, evenings & weekends was added to routes 23B & 23T, replacing most of the route 23A service.[9] 23A now operates only during the early mornings and late nights.

Due to the West Glebe Road bridge construction, service will be rerouted via West Glebe Road at the City of Alexandria on December 30, 2018.[10] Routes 23A and 23B no longer operates through Avalon Bay at South Glebe Road.

In response to the COVID-19 pandemic, routes 23A, 23B, and 23T went on major service modification to simplify routes. The line operated on its Sunday schedule during the pandemic. The 23A, 23B and 23T weekend service was also suspended to limit its service. WMATA later announced to restore the line on August 23, 2020 as part of the Metro's COVID-19 Recovery Plan.[11] However, some changes were made on the line, with the 23A operating on full weekdays, and the 23B and 23T only operating during weekends. This marks the 23A operating on full day for the first time since 2016, when the 23A was replaced by the 23B and 23T. No route segment changes was made, as the 23A retains the same intervals and same stops as the late night schedules.

On September 10, 2020 as part of its FY2022 proposed budget, WMATA proposed to reduce all weekend frequencies on routes 23A, 23B, and 23T service in order to reduce costs and low federal funds.[12]