At that point, the railroad was above the Fall Line and was able to follow a more direct northwesterly course in Virginia through Dunn Loring, Vienna, Sunset Hills (now in Reston), Herndon, Sterling, Ashburn and Leesburg.

It served as a local carrier that was extensively used and fought over during the Civil War; served Washington vacationers headed to the Blue Ridge mountains; hauled agricultural products into Washington; aided the development of Falls Church and Dunn Loring; and, at the end of its operational life, hauled materials used in the construction of Dulles Airport and the Capital Beltway.

In 1853 the charter of the A&HF was amended to change the name to the Alexandria, Loudoun and Hampshire (AL&H) Railroad and change the route to pass as close as possible to Leesburg, then through Clarke's Gap and into the Blue Ridge Mountains through the Bloomery Gap of Cacapon to Paddytown in what is now West Virginia and there connect with a railroad serving the coal fields.

[3] Still intending to cross the Blue Ridge Mountains and the Shenandoah River to reach the coal fields that are now within Mineral County, West Virginia, the AL&H began operating to Vienna in 1859 from a terminal near Princess and Fairfax Streets in Alexandria's present Old Town neighborhood.

At the end of the war, the railroad helped transport the Army of the Potomac back to Washington and on August 8, 1865, it was returned to its original owners.

At the same time, the line was extended to Hamilton (then called Irene Station) and passenger service was doubled[7] In 1874, the line was extended to Purcelleville and then Round Hill, grading began on the Winchester extension (which included a cup through rocks at Scotland Gap between Round Hill and Snickersville) and a new 131-foot Howe truss bridge was erected over Broad Run.

[10][8] During this time, President Grover Cleveland frequently rode the train to Leesburg to fish and the town of Dunn-Loring was platted along the tracks.

[11][12][13] In 1900, the Southern Railway extended the line westward for four miles from Round Hill to Snickersville, which was then renamed Bluemont; but abandoned all plans to go to West Virginia.

[11] On weekends, express trains carried vacationers from Washington to Bluemont and other towns in western Loudoun County in which resorts had developed.

[11][12][15] Meanwhile, in 1906, electric trolleys began to run on the Great Falls and Old Dominion Railroad (GF&OD) northwest to Great Falls from Georgetown in Washington, D.C.[16][17] The line, which John Roll McLean and Stephen Benton Elkins owned at the time, crossed the Potomac River on the old Aqueduct Bridge and passed through Rosslyn.

[20] The W&OD electrified all of its operations over the next four years, becoming an interurban electric trolley system that carried passengers, mail, milk and freight.

Some of the Bluemont Division cars or trains then continued their trips through Falls Church, Vienna, Herndon, Sterling, Ashburn, Leesburg, Clarke's Gap and Purcellville to terminate in Bluemont, Virginia, at the base of the Blue Ridge Mountains, following a route that was similar to that of Virginia State Route 7.

[29] Stationary and movable electrical substations containing Westinghouse alternating current (AC) to DC converters were located at Round Hill, Leesburg, Herndon, and Bluemont Junction.

In 1941, not only did the railroad end passenger service (temporarily, as it would turn out), but it began to convert its operations from electric to diesel or gasoline power; a process that it completed in 1944.

The retrenchment and diesels, coupled with growth in Arlington – and an accompanying increased demand for building supplies – led to, starting in 1940, the first profits in 28 years.

[47][48] After finding few riders, the railroad asked to discontinue passenger service in June, noting that it was using gasoline, which was also being curtailed for the war, but their request was denied.

[58] The highway department began negotiations to purchase the Rosslyn spur in 1960 and was trying to buy the mainline as early as 1962 for the construction of a road that was to become Interstate 66 (I-66).

The Northern Virginia Transportation Commission (NVTC), which was interested in converting the line to a commuter rail service, also opposed the purchase.

Clive L. DuVal II (Fairfax-Falls Church) and WMATA secured a 60-day postponement of the abandonment while they put together a plan to use the right-of-way for transit.

But a temporary restraining order kept the line open until the U.S. District Court in Alexandria sustained the decision in July setting the last for August 27, 1968.

[71] After the W&OD stopped running passenger trains in 1951, the Dunn Loring station served as the town's post office, but was then torn down in 1963.

[79] In August 1970, the 80 year old East Falls Church station, located south of the tracks on the west side of Washington Street/Lee Highway (now Langston Boulevard), was torn down also to make room for I-66 and the Metrorail line.

The Bluemont line traveled along Four Mile Run on the east side and perpendicular to the flow of water on the west which resulted in numerous bridges.

The stone abutments and piers date from the original pre-Civil War period of construction, but other components have been replaced several times, most recently in 1981 when the current bridge span was built.

[2] Additionally, abutments carrying an old road over the tracks can be found in Loudoun County between Crosstrail Boulevard and the access trail to Rhonda Place, SE.

Located at the center of Ayr Hill and Dominion Roads, the Vienna Train Depot has served as the home of the Northern Virginia Model Railroaders Club since 1975.

[107][109] The Bluemont station burned down in 1920, but the grain elevator was left standing (and later built taller to serve as cell phone tower).

[111] The spur formerly served trains traveling from the eastern end of the Bluemont Division to the Southern Railway's freight and passenger stations in old town Alexandria.

[111] Railroad operations ended on the spur in 2012–2013 when GenOn Energy's Potomac River Generating Station and the Robinson Terminal's Oronoco Street warehouse closed.

Until 2023 some of the warehouses along the old W&OD in Alexandria (between Calvert and Swann) that were built to be serviced by it – with doors that opened toward the railroad – remained, but they were torn down to make room for the Del Ray Corner development.