Manassas and Roanoke were created because of railroad junctions. The Manassas Gap Railroad was not intended to connect with the Orange and Alexandria. A level roadbed was graded through Fairfax, but the Panic of 1857 forced the backers of the Manassas Gap Railroad to economize. Costs for construction of 20-25 miles of track was eliminated by the decision to intersect the O&A at a place named Manassas Junction.
Orange and Alexandria Railroad route south of Bull Run
(before "Tudor Hall" evolved into Manassas)
Source: Library of Congress
In the Civil War, the Confederates burned the facilities at the junction in March - and in August of 1862, after the Yankees had built new warehouses. During the Overland Campaign of 1864-64, when Grant finally captured Richmond, the site was largely abandoned.
After the Civil War, however, the junction developed into a bustling community. It was chartered as a town in 1875, and soon thereafter managed to get the county seat moved from Brentsville to Manassas. Brentsville had been bypassed by the O&A Railroad because it was on a high spot, and railroads were constructed to avoid hills wherever possible. Unlike Warrenton, county seat of Fauquier, Brentsville was unable to get a spur line built to the county seat and, in the end, disappeared from the map.
in the 1950's the Orange and Alexandria Railroad bypasse the county seats of Fairfax, Prince William, and Fauquier counties in order to build track on a more-level ground, and only Warrenton justified building a spur track
Source: Library of Congress, Colton's Virginia (by J. H. Colton, 1855)
Roanoke was the last "central city" to develop in Virginia. It developed after the landowners around "Big Lick" decided the wanted the Shenandoah Valley Railroad to intersect the Norfolk and Western (the former Virginia and Tennessee) at their location. Nearby Salem was not interested in becoming a rowdy railroad town, but the landowners just downstream on the Roanoke River welcomed the economic stimulus of the railroad business.
No railroad crossed the Shenandoah Valley, uniting the James and Potomac rivers, until after the Civil War. Pre-war Virginia politicians blocked projects that would steer trade to Baltimore rather than Richmond, Petersburg, Norfolk, or Alexandria. After the war, Northern financiers had sufficient economic leverage and political influence in the General Assembly to build a new north/south railroad and merge it into the Norfolk and Western in 1881-2.
The junction of the railroads could have been located as far east as Bedford or even Lynchburg, but economically it made sense to reduce the milegage of parallel track and unite the lines west of the Roanoke River water gap through the Blue Ridge. So topography, as well as politics, determined where the junction would occur.
Had the railroad been limited to just the farm trade of the Shenandoah Valley and Southwest Virginia, Roanoke may never have grown into a city of 100,000 people. Its growth is attributable to the development of the rich coal veins of the Appalachian Plateau in West Virginia and Tazewell, Buchanan, Dickinson, and Wise counties in Virginia. Demand was so great that at Pocahontas, the coal was mined and stockpiled on the route of the railroad in advance of the tracks being laid down and trains arriving in 1883. The Norfolk and Western RR located its locomotive manufacturing and repair shops in Roanoke, and the city grew so rapidly that it was knows as the "Magic City" at the turn of the century (1900).
In contrast, the population of Manassas did not boom, and few railroad workers lived there. Manassas had a crew change facility and a depot, but the railroad repair facilities were in Alexandria.
In 2018, with population swelling as the city has been "swallowed" by the Washington megalopolis, the population of Manassas remained half that of Roanoke. Manassas remained a town until 1975, when it obtained a city charter. The major employer at the time was IBM, which hired mstly white-collar rather than blue-collar wrkers. Because there were so few industrial laborers in Manassas, the city's politics have been substantially different from that of Roanoke.
Leadership in Manassas was part of the Byrd Organization until the 1970's. Manassas shifted from a town to city status in 1975, two years after the state parties finally aligned with their national parties, and Virginia Republicans finally identified themselves as the "conservative" alternative to "liberal" Democrats. The Manassas City Council elected Republicans and Independents, but no one who advertised as a Democrat from 1975 until the 2014 election.
Roanoke has been much more of a blue-collar union town, reflecting its manufacturing heritage. That city has consistently recorded a strong Democratic majority in elections.
Newport News developed as an urban center after the Chesapeake and Ohio Railroad was extended from Richmond
Source: University of North Carolina, The Great South; A Record of Journeys in Louisiana, Texas, the Indian Territory, Missouri, Arkansas, Mississippi, Alabama, Georgia, Florida, South Carolina, North Carolina, Kentucky, Tennessee, Virginia, West Virginia, and Maryland (1875)