Loudoun County Transit (LC Transit) is a public-transportation service provided by the Loudoun County, Virginia government. Loudoun County Transit provides fixed routes and on-demand/paratransit bus service. The buses operate from Dulles, Leesburg, and Purcellville to Washington Metro stations as well as directly to Rosslyn, Virginia, The Pentagon, and Washington, D.C. The service utilizes buses that are permitted to travel on the express lanes of the Dulles Toll Road, unlike normal traffic. This allows for a shorter trip and also bypasses commuter tolls. The Loudoun County Commuter Bus accepts payment via SmarTrip, a reloadable transit card issued by the Washington Metropolitan Area Transit Authority. Loudoun County Transit buses also operates local bus service through Sterling, Ashburn, and Leesburg, providing connections to Silver Line metro stations. Virginia Regional Transit only operates the Purcellville Connector that is part of local bus service. LC Transit uses long buses (seating around 50) with white and metal trim and display the LC Transit logo, while VRT buses are short (seating around 15) and have a predominantly white and maroon color scheme, frequently without a logo. Local buses are around the same size as VRT buses & have the LC Transit logo.

Routes