Richmond Highway Express, nicknamed "REX" is a bus route operated by the WMATA (the Washington Metropolitan Area Transit Authority) in partnership with Fairfax County, the City of Alexandria, the Commonwealth of Virginia and the Federal Government. The REX is a limited stop express bus that serves the Richmond Highway corridor. Before the REX, riders from Fort Belvoir had many stops to make along Richmond Highway enroute to Huntington Metrorail Station and to the King Street Metrorail Station.

REX buses operate every 15 minutes in both directions on Richmond Highway during weekday rush hours. During non-rush hours and on Satuday the REX comes through every 30 minutes. Then on Sunday the bus only operates every 60 minutes. Buses operate between 5:30 AM and 10:00 PM Monday through Saturday, and 5:30 AM to 9:30 PM on Sunday.

The REX uses special technology which allows REX buses to sustain green lights in order to move more quickly up and down Rt. 1. The REX bus has low-floor buses for quicker boarding and SmartCard for quicker paying. In addition the REX has only a limited number of stops:

• King Street Metro (Alexandria)
• Dulaney Street/PTO (Alexandria)
• Eisenhower Avenue (Alexandria)
• Kings Highway
• Beacon Center
• Lockheed Boulevard
• Arlington Drive
• Belford Drive South
• Ladson Lane
• South County Center
• Frye Road
• Lukens Lane
• Sacramento Drive/Cooper Road
• Old Mill Road/Mt. Vernon Memorial Highway
• Dewitt Hospital (Fort Belvoir)
• Langfitt Loop (Fort Belvoir)
• 16th Street & Belvoir Road (Fort Belvoir)
• Jackson Loop (North) & Gunston Road (Fort Belvoir)

REX passengers may transfer at any Richmond Highwaystop to Fairfax Connector routes, and may transfer at Huntington and King Street Metro stationsto rail service as well as other local bus service such as Alexandria’s DASH.

To stand-out from other Metrobuses and other area bus lines, REX busses are purple-blue with a golden yellow logo featuring the image of a running lion. The lion references the three lions emblazoned on the Fairfax County seal, which references the family crest of Lord Fairfax. Bus stop signs use the same color scheme, and stand out among the other bus stops along Route 1.