Long Bridge is the common name used for three successive bridges connecting Washington, D.C., to Arlington, Virginia, over the Potomac River. The first was built in 1808 for foot, horse and stagecoach traffic, and bridges in the vicinity were repaired and replaced several times in the 19th century. The current bridge was built in 1904 and substantially modified in 1942. It has only been used for railroad traffic and is owned by CSX Transportation. It is used by CSX freight trains, Amtrak intercity trains and Virginia Railway Express commuter trains. Norfolk Southern Railway also has trackage rights on the bridge but does not currently exercise those rights. In 2019 Virginia announced that it would help fund and build a new rail bridge parallel to the existing one to double its capacity, following the plans that have been studied by the District Department of Transportation (DDOT) and Federal Railroad Administration (FRA) since 2011.

Virginia Railway Express (VRE) is a commuter rail service that connects outlying small cities of Northern Virginia to Union Station in Washington, D.C. It operates two lines which run during weekday rush hour only: the Fredericksburg Line from Spotsylvania, Virginia, and the Manassas Line from Broad Run station in Bristow, Virginia. In 2023, the system had a ridership of 1,537,000, or about 5,900 per weekday as of the fourth quarter of 2023.