Baltimore and Ohio Railroad system map, circa 1961
|Dates of operation||1828–1987|
|Track gauge||4 ft 8 1⁄2 in (1,435 mm)|
The Baltimore and Ohio Railroad ( reporting marks B&O, BO) was the first common carrier railroad and the oldest railroad in the United States, with its first section opening in 1830. It came into being mostly because the city of Baltimore wanted to compete with the newly constructed Erie Canal (which served New York City) and another canal being proposed by Pennsylvania, which would have connected Philadelphia and Pittsburgh. At first this railroad was located entirely in the state of Maryland, with an original line built from the port of Baltimore west to Sandy Hook.
At this point to continue westward, it had to cross into Virginia (now West Virginia) over the Potomac River, adjacent to the confluence of the Potomac and Shenandoah rivers. From there it passed through Virginia from Harpers Ferry to a point just west of the junction of Patterson Creek and the North Branch Potomac River, where it crossed back into Maryland to reach Cumberland. From there it was extended to the Ohio River at Wheeling and a few years later also to Parkersburg, West Virginia. It continued to construct lines into Ohio, including a junction at Portsmouth. In later years, B&O advertising carried the motto: "Linking 13 Great States with the Nation."
As part of a series of mergers, the B&O is now part of the CSX Transportation (CSX) network. The B&O also included the Leiper Railroad, the first permanent horse-drawn railroad in the U.S. At the end of 1970, the B&O operated 5,552 miles of road and 10,449 miles of track, not including the Staten Island Rapid Transit (SIRT) or the Reading and its subsidiaries. It includes the oldest operational railroad bridge in the United States.
When CSX established the B&O Railroad Museum as a separate entity from the corporation, it donated some of the former B&O Mount Clare Shops in Baltimore, including the Mt. Clare roundhouse, to the museum, while selling the rest of the property. The B&O Warehouse at the Camden Yards rail junction in Baltimore now dominates the view over the right-field wall at the Baltimore Orioles' current home, Oriole Park at Camden Yards. Part of the B&O Railroad's immortality has come from being one of the four featured railroads on the U.S. version of the board game Monopoly. It is the only railroad on the board that did not directly serve Atlantic City, New Jersey.
- 1 History
- 2 Conflicts in the early years
- 3 Branches
- 4 See also
- 5 References
- 6 Further reading
- 7 External links
The fast-growing port city of Baltimore, Maryland faced economic stagnation unless it opened routes to the western states, as New York had done with the Erie Canal in 1820. On February 12, 1827, twenty-five merchants and bankers studied the best means of restoring "that portion of the Western trade which has recently been diverted from it by the introduction of steam navigation."  Their answer was to build a railroad—one of the first commercial lines in the world. 
Their plans worked well, as the railroad grew from a capital base of $3 million in 1827 to a large enterprise generating $2.7 million of annual profit on its 380 miles (610 km) of track in 1854, with 19 million passenger miles. The railroad fed tens of millions of dollars of shipments to and from Baltimore and its growing hinterland to the west, thus making the city the commercial and financial capital of the region south of Philadelphia. 
Two men — Philip E. Thomas and George Brown — were the pioneers of the railroad.   They spent the year 1826 investigating railway enterprises in England, which were at that time being tested in a comprehensive fashion as commercial ventures.  Their investigation completed, they held an organizational meeting on February 12, 1827, including about twenty-five citizens, most of whom were Baltimore merchants or bankers.  Chapter 123 of the 1826 Session Laws of Maryland, passed February 28, 1827, and the Commonwealth of Virginia on March 8, 1827, chartered the Baltimore and Ohio Rail Road Company, with the task of building a railroad from the port of Baltimore west to a suitable point on the Ohio River. The railroad, formally incorporated April 24, was intended to provide a faster route for Midwestern goods to reach the East Coast than the hugely successful but slow Erie Canal across upstate New York. Thomas was elected as the first president and Brown the treasurer. The capital of the proposed company was fixed at five million dollars,  but the B&O was initially capitalized in 1827 with a three million dollar issue of stock. Virtually every citizen of Baltimore owned a share, as the offering was oversubscribed. 
Construction began on July 4, 1828, when Charles Carroll of Carrollton did the groundbreaking. The initial tracks were built with granite stringers topped by strap iron rails. The first section, from Baltimore west to Ellicott's Mills (now known as Ellicott City), opened on May 24, 1830. Developers decided to follow the Patapsco River to a point near Parr's Ridge (now known as Mount Airy), where the railroad would cross a height of land and descend into the valley of the Monocacy and Potomac rivers. Further extensions opened to Frederick (including the short Frederick Branch) December 1, 1831; Point of Rocks April 2, 1832; Sandy Hook December 1, 1834 (the connection to the Winchester and Potomac Railroad at Harpers Ferry opening in 1837); Martinsburg May 1842; Hancock June 1842; Cumberland November 5, 1842; Piedmont July 21, 1851; Fairmont June 22, 1852; and its terminus at Wheeling, West Virginia (then part of Virginia) on January 1, 1853. The narrow strip of available land along the Potomac River from Point of Rocks to Harpers Ferry caused a legal battle between the B&O and the Chesapeake and Ohio (C&O) Canal, as both sought to exclude the other from its use.  A later compromise allowed the two companies to share the right of way.
The State of Maryland granted the B&O a charter to build a line from Baltimore to Washington, D.C., in 1831, and the Washington Branch was opened in 1835. :157 This line joined to the original mainline at Relay, Maryland, crossing the Patapsco on the Thomas Viaduct, which remains one of the B&O's signature structures. This line was partially funded by the state, and was operated separately until the 1870s, with the state taking a 25 percent cut of gross passenger receipts. This line was built in stone, much like the original mainline. By this time, however, strap rail was no longer used for new construction. Most of the stone bridges on the Old Main Line did not last long, being washed out by the periodic flooding of the Patapsco River and replaced at first by Bollman Truss bridges. The Annapolis and Elk Ridge Railroad to Annapolis connected to this line at Annapolis Junction in 1840. As an unwritten condition for the charter, it was understood that the state would not charter any competing line between Baltimore and Washington.
When construction began on the B&O in the 1820s, railroad engineering was in its infancy. Unsure exactly which materials would suffice, the B&O erred on the side of sturdiness and built many of its early structures of granite. Even the track bed to which iron strap rail was affixed consisted of the stone.
Though the granite soon proved too unforgiving and expensive for track, most of the B&O's monumental bridges have survived to this day, and many are still in active railroad use by CSX. Baltimore's Carrollton Viaduct, named in honor of Charles Carroll of Carrollton, was the B&O's first bridge, and is the world's second-oldest railroad bridge still carrying trains (the world's oldest is the Skerne Bridge, Darlington, UK of 1824-1825).  The Thomas Viaduct in Relay, Maryland, was the longest bridge in the United States upon its completion in 1835. It also remains in use. The B&O made extensive use of the Bollman iron truss bridge design in the mid-19th century. Its durability and ease of assembly aided faster railroad construction.
As the B&O built the main line west to Parrs Ridge, it had limited information about the operation of steam locomotives. Consequently, the company was uncertain if the engine's metal wheels would grip the metal rails sufficiently to pull a train up to the top of the ridge. The railroad decided to construct two inclined planes on each side of the ridge along which teams of horses, and perhaps steam-powered winches, would assist pulling the trains uphill. The planes, about a mile long on each side of the ridge, quickly proved an operational bottleneck. Before the decade of the 1830s ended, the B&O built a 5.5-mile-long (8.9 km) alternate route that became known as the Mount Airy Loop. The planes were quickly abandoned and forgotten, though some artifacts survive to the present.
See also Old Main Line Subdivision
In 1843, Congress appropriated $30,000 for construction of an experimental 38-mile (61 km) telegraph line between Washington, D.C., and Baltimore along the B&O's right-of-way. The B&O approved the project with the agreement that the railroad would have free use of the line upon its completion. An impressive demonstration occurred on May 1, 1844, when news of the Whig Party's nomination of Henry Clay for U.S. President was telegraphed from the party's convention in Baltimore to the Capitol Building in Washington. On May 24, 1844, the line was officially opened as Samuel F. B. Morse sent his famous words, "What hath God wrought", from the B&O's Mount Clare station to the Capitol by telegraph. 
Contrary to legend, the B&O was not the first chartered railroad in the United States; John Stevens obtained a charter for the New Jersey Railroad in 1815.  The B&O was, however, the first company to operate a locomotive built in America, with the "Tom Thumb" in 1829. It built the first passenger and freight station (Mount Clare in 1829) and was the first railroad to earn passenger revenues in December 1829, and publish a timetable on May 23, 1830. On Christmas Eve 1852, the B&O line was completed between Baltimore and the Ohio River near Moundsville, West Virginia. 
Operation of the railroad was hampered by its partial government ownership. Of the thirty members on its board of directors, twelve were elected by shareholders, while the other eighteen were appointed either by Maryland or the Baltimore City Council.  They had conflicting interests: the directors appointed by the state and city desired low fares and all construction to be funded from corporate revenues, while the directors elected by shareholders desired greater profits and dividends. These conflicts became more intense in the 1850s after the completion of the C&O Canal, which brought additional competition to the B&O for transport services. In 1858, after being nominated by large shareholder and director Johns Hopkins, John W. Garrett became president of the B&O, a position he would hold until his death in 1884.  In the first year of his presidency, corporate operating costs were reduced from 65 percent of revenues to 46 percent,  and the railroad began distributing profits to its shareholders.
Abolitionists stopped a train during John Brown's raid on the federal arsenal at Harpers Ferry, Virginia (later part of West Virginia).  Garrett telegraphed the Secretary of War, and a B&O train carried federal troops led by Robert E. Lee to capture the abolitionists and John Brown.  
At the outset of the Civil War, the B&O possessed 236 locomotives, 128 passenger coaches, 3,451 rail cars and 513 miles (826 km) of rail road, all in states south of the Mason–Dixon line. Although many Marylanders had Southern sympathies, Garrett and Hopkins supported the Union. The B&O was instrumental in supporting the Federal government during the Civil War, as it was the main rail connection between Washington, D.C., and the northern states. As a result, 143 raids and battles during the war involved the B&O Railroad, many resulting in substantial loss.
Confederate operations began in May with Colonel Jackson's operations against the B&O Railroad (1861). By the end of 1861, 23 B&O railroad bridges had been burned, 102 miles (164 km) of telegraph line were cut down, 36.5 miles (58.7 km) of track was torn up or destroyed, 42 locomotives were burned, 14 locomotives were captured and 386 rail cars stolen and destroyed. Through these actions, operations on B&O Railroad were completely shut down for ten months. It was not until the end of March 1862 that service on the B&O Railroad was restored, and even then train movements were sporadic and subject to frequent stoppages, derailments, capture and attack. Prominent raids on the B&O railroad during this period were:
- The Great Train Raid of 1861, May 22 – June 23, 1861
- The Romney Expedition, January 1 through January 24, 1862
- Operations during the Maryland Campaign, September 8, 1862
- Various raids of Brigadier General A. G. Jenkins, Fall, 1862
B&O Locomotives Captured During the Great Train Raid of 1861 Engine Name Eng. No. Type ? No. 17 Norris 4-2-0 ? No. 34 Mason 4-4-0 ? No. 187 Camel 0-8-0 Lady Davis (CSA name) No. 188 Tyson 4-4-0 "Dutch Wagon" ? No. 193 Camel 0-8-0 ? No. 198 Hayes Camel 0-8-0 ? No. 199 Camel 0-8-0 ? No. 201 ?
The second half of the Civil War was characterized by near continuous raiding, which severely hampered the Union defense of Washington, D.C. Union forces and leaders often failed to properly secure the region, despite the vital importance of the rail company to the Union cause.
"There is no interest suffering here except the Baltimore and Ohio Railroad and I will not divide my forces to protect it."
This military strategy, or lack thereof, allowed Confederate commanders to contribute significantly to the length of the war, by conducting free-ranging military operations against the region and railroad.
The B&O and Garrett are particularly remembered for their part in the Battle of Monocacy. Agents of the railroad began reporting Confederate troop movements eleven days prior to the battle, and Garrett had their intelligence passed to authorities in the War Department and to Major General Lew Wallace, who commanded the department that would be responsible for defense of the area. As preparations for the battle progressed, the B&O provided transport for federal troops and munitions, and on two occasions Garrett was contacted directly by President Abraham Lincoln for further information. Though Union forces lost this battle, the delay allowed Ulysses S. Grant to successfully repel the Confederate attack on Washington at the Battle of Fort Stevens two days later. After the battle, Lincoln paid tribute to Garrett as:
"The right arm of the Federal Government in the aid he rendered the authorities in preventing the Confederates from seizing Washington and securing its retention as the Capital of the Loyal States."— Abraham Lincoln 
- The Jones-Imboden Raid, April 24 through May 22, 1863
- The Catoctin Station Raid, June 17, 1863
- The First Calico Raid, June 19, 1863
- The B&O Raid on Duffield Station, January 1864
- The McNeill Raid, May 5, 1864
- The Second Calico Raid, July 3, 1864
- The Battle of Monocacy, July 9, 1864
- Gilmor's Raid, July 11, 1864
- The Greenback Raid, by Mosby's Rangers on October 14, 1864
- The B&O Raid on Duffield Station II, January 1865
- Gilmor's B&O Raid, February 1865
- The B&O Derailment Raid, March 1865
The Confederate leaders who led these operations and specifically targeted the railroad included:
- Lieutenant General Thomas J. "Stonewall" Jackson and many units under his command
- Lieutenant General Jubal Anderson Early and many units under his command
- Brigadier General Turner Ashby and his "Black Horse" cavalry
- Brigadier General John D. Imboden and the 62nd Virginia Mounted Infantry (1st Partisan Rangers)
- Brigadier General Albert G. Jenkins and the 8th Virginia Cavalry
- Brigadier General William E. "Grumble" Jones and the "Laurel Brigade"
- Colonel John S. Mosby's " Mosby's Rangers"
- Major Harry Gilmor's "Gilmor's Raiders"
- Captain John H. McNeill's " McNeill's Rangers"
Bases of operation involved in raiding the B&O Railroad:
A steel and stone bridge was built across the Ohio River between Bellaire, Ohio and Wheeling, West Virginia in 1871, connecting the B&O to the Central Ohio Railroad, which the B&O had leased starting in 1866. This provided a direct rail connection to Columbus, Ohio, and the lease marked the beginning of a series of expansions to the west and north.
Other railroads included in the B&O were:
- Winchester and Potomac Railroad and Winchester and Strasburg Railroad from 1867. This pair of lines connected with the B&O at Harper's Ferry, West Virginia, and constituted the only significant B&O trackage in present-day Virginia.
- Sandusky, Mansfield and Newark Railroad leased through the Central Ohio in 1869
- Pittsburgh and Connellsville Railroad from 1871. This was the B&O entry into Pittsburgh, thwarting the denial of a Pennsylvania charter to the B&O.
- Somerset and Cambria Railroad from 1879
- Buffalo Railroad from 1880
- Pittsburgh Southern Railroad acquired 1883. Originally a narrow gauge railroad, it was converted to standard gauge and renamed the Baltimore & Ohio Short Line.
- West Virginia and Pittsburgh Railroad from 1890
- Columbus and Cincinnati Midland Railroad leased through the Central Ohio in 1890
- Monongahela River Railroad from 1900
- Marietta and Cincinnati Railroad from 1882. This was initially renamed the Cincinnati, Washington and Baltimore Railroad and then again to the Baltimore and Ohio Southwestern Railroad in 1889. The B&OSW absorbed the Ohio and Mississippi Railroad in 1893, giving the B&O a connection to St. Louis, Missouri, and finally the B&OSW disappeared into the rest of the system in 1900.
- Ohio River Railroad from 1901
- Pittsburgh Junction Railroad from 1902
- Pittsburgh and Western Railroad from 1902. This was originally a narrow gauge system which was standard gauged from 1883 to 1911. It formed the main B&O line west from Pittsburgh. The line passed the Mars Train Station in Mars, Pennsylvania, northwest of Pittsburgh.
- Cleveland, Terminal and Valley Railway from 1895. This was the B&O's entry into Cleveland, Ohio.
- Cleveland, Lorain and Wheeling Railroad from 1909
- Chicago Terminal Transfer Company, reorganized in 1910 as the Baltimore and Ohio Chicago Terminal Railroad. This switching line was always operated as a separate company.
- Salisbury Railroad near Pittsburgh, operated from 1912
- Cincinnati, Hamilton and Dayton Railroad from 1912
- Morgantown and Kingwood Railroad from 1920 
- Coal and Coke Railway from 1916 
- Cincinnati, Indianapolis and Western Railroad from 1927. This was originally part of the Cincinnati, Hamilton and Dayton, and gave the B&O a connection to Springfield, Illinois.
- Buffalo, Rochester and Pittsburgh Railway in 1932. This gave the B&O a line into New York state.
- Buffalo and Susquehanna Railroad from 1932. Part of the line was severed from the rest of the system by flooding, and became part of the Wellsville, Addison and Galeton Railroad in 1955.
(This list omits certain short lines.)
The Chicago and Alton Railroad was purchased by the B&O in 1931 and renamed the Alton Railroad. It was always operated separately and was eventually bought by the Gulf, Mobile and Ohio Railroad after receivership in 1942.
As a result of poor national economic conditions in the mid-1870s following the Panic of 1873, the B&O attempted to reduce its workers' wages. After a second reduction in wages was announced in the same year, workers began the Great Railroad Strike of 1877 on July 14 in Martinsburg, West Virginia. The strike spread to Cumberland, and when the governor of Maryland on July 20 attempted to put down the strike by sending the state militia from Baltimore, riots broke out resulting in 11 deaths, the burning of parts of Camden station, and damage to several engines and cars.  The next day workers in Pittsburgh staged a sympathy strike that was also met with an assault by the state militia; Pittsburgh then erupted into widespread rioting. The strike ended after federal troops and state militias restored order.
In 1866 the B&O began constructing the Metropolitan Branch west out of Washington, and was completed in 1873 after years of erratic effort. Before this line was laid, rail traffic west of Washington had to travel first to Relay or Baltimore before joining the main line. The line cut a more or less straight line from Washington to Point of Rocks, Maryland, with many grades and large bridges. Upon the opening of this line, through passenger traffic was rerouted through Washington, and the Old Main Line from Point of Rocks to Relay was reduced to secondary status as far as passenger service was concerned. The Washington to Gaithersburg section of the Met Branch was double-tracked during 1886–1893.  Rebuilding in the early 20th century and complete double tracking of the branch by 1928 increased capacity; the "branches" became the de facto mainline, though the Old Main Line was retained as a relief route.
Meanwhile, the Pennsylvania Railroad (PRR) outmaneuvered the B&O to acquire the B&O's northern connection, the Philadelphia, Wilmington and Baltimore Railroad in the early 1880s, cutting off the B&O's access to Philadelphia and New York. The state of Maryland had stayed true to its implicit promise not to grant competing charters for the Baltimore/Washington line, but when a charter was granted in 1860 to build a line from Baltimore to Pope's Creek in southern Maryland, lawyers for the Pennsylvania RR picked up on a clause in the unfulfilled charter allowing branches up to 20 miles (32 km) long, from any point and in any direction. The projected route, passing through what is now Bowie, Maryland, could have a "branch" constructed that would allow service into Washington. The Pennsylvania picked up the charter through the agency of the Baltimore and Potomac Railroad and in 1872 service between Baltimore and Washington began. (See Pope's Creek Subdivision.) At the same time the PRR outmaneuvered the B&O and took control of the Long Bridge across the Potomac River into Virginia, the B&O's connection to southern lines.
In response, the B&O chartered the Philadelphia Branch in Maryland and the Baltimore and Philadelphia Railroad in Delaware and Pennsylvania and built a parallel route, finished in 1886. The Baltimore Belt Line, opened in 1895, connected the main line to the Philadelphia Branch without the need for a car ferry across the Patapsco River, but the cost of constructing the Howard Street Tunnel drove the B&O to bankruptcy in 1896. Two other lines were built in attempts to reconnect to the south. The Alexandria Branch (now called the Alexandria Extension) was built in 1874, starting from Hyattsville, Maryland, and ending at a ferry operation at Shepherd's Landing. The ferry operation continued until 1901 when the trackage rights agreement concluded as part of the construction of Washington Union Station saw the south end of the branch realigned to link to the PRR trackage in Anacostia, across the Anacostia Railroad Bridge, into the Virginia Avenue Tunnel, through Southwest Washington, D.C. to Potomac Yard in Alexandria, Virginia. (See RF&P Subdivision.) The Alexandria Branch trackage to Shepherd's Landing was heavily used during World War II when traffic congestion on the Long Bridge caused the U.S. Army Corps of Engineers to construct a bridge along the original plan of the B&O: Alexandria to Shepherd's Landing, Washington. Trains of empty freight cars were routed north and south over the structure, which was demolished after the end of World War II. 
Before either connection was made, however, another branch was built around the west side of Washington. During the 1880s the B&O had organised a group of bankrupt railroads in Virginia into the Virginia Midland Railroad. The VM track ran from Alexandria to Danville, Virginia. The line projected west across the Potomac River was intended to cross the Potomac just north of the D.C. line, to continue southwest to a connection with the B&O-controlled Virginia Midland (VM) in Fairfax (now Fairfax Station, to distinguish it from what was Fairfax Court House and is now the City of Fairfax, Virginia), and if possible to a connection with the Richmond, Fredericksburg and Potomac Railroad in Quantico. The branch was started in 1892 and reached Chevy Chase, Maryland, the same year. Financial problems in both the VM and B&O forced a halt to construction and led to the B&O's loss of control of the VM. Following bankruptcy, and control by the Pennsylvania Railroad, by the time the line was completed in 1910 there was no longer any point to the river crossing. Thus, the renamed Georgetown Branch came to serve a wide range of customers in Maryland and in Georgetown, such as the Potomac Electric Power Company, the Washington Milling Company, and the U.S. government. The line cut directly across various creeks, and includes what was said to be the longest wood trestle on the railroad over Rock Creek; and a short tunnel, Dalecarlia Tunnel, under the Washington Aqueduct. The line was almost completely abandoned in 1986 by CSX and is presently used in part as the right-of-way for the Capital Crescent Trail.
After a flood damaged the C&O Canal in 1877, the B&O acquired a majority interest in the canal mainly to keep its property and right of way from potential use by the Western Maryland Railroad.  The canal was operated by the B&O until 1924 when it was damaged in another flood. The canal's property was later transferred to the U.S. government in 1938 in consideration for obtaining a loan from the federal Reconstruction Finance Corporation. 
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Following its emergence from bankruptcy, control of the B&O was acquired by the Pennsylvania Railroad in 1901. A rising young PRR Vice President, Leonor F. Loree, was appointed President. Loree shared the Pennsy management's belief in infrastructure and the B&O at that time needed some of that. New classes of engines were built to haul longer, heavier trains faster. The Old Main Line was reworked, sections of the original right-of-way cut off by the straightening of curves and replacement of old, weight-restricted bridges with newer, heavier bridges. Most of Loree's work on the B&O physical plant remains evident today. Many iron and steel bridges on the railroad were replaced with stone (Pennsy preferred stone to the preference of the Reading and Lackawanna Railroad for concrete).
The railroad's passenger numbers were at a disadvantage with the railroad's major competitor in the northeast, the Pennsylvania Railroad. That railroad had a tunnel into Manhattan, thus carrying passengers directly into New York City. The B&O had no tunnel rights, and its New York City market trains actually terminated at the Central Railroad of New Jersey Terminal in Jersey City. From Philadelphia to Jersey City the B&O traveled over Reading Railroad tracks to Bound Brook and there joining Central Railroad of New Jersey tracks to Jersey City. Passengers rode CNJ ferries on B&O busses to Manhattan. Suffering from the its weaker market position from Baltimore to New York, the B&O discontinued all passenger service north of Baltimore on April 26, 1958.
The Chesapeake and Ohio Railway took financial control of the B&O in 1963. The B&O already had a controlling interest in the Western Maryland Railway. In 1973 the three railroads were brought together under one corporate identity, the Chessie System, although they continued to operate as separate railroads. The Western Maryland was merged into the B&O in 1976. In 1980 the Chessie System and Seaboard Coast Line Industries, a holding company that owned the Seaboard Coast Line, the Louisville & Nashville, the Clinchfield, and the Georgia Railroad, agreed to form CSX Corporation. SCL Industries was renamed the Seaboard System Railroad (SBD) in 1983, the same year that the Western Maryland Railway was completely absorbed into the B&O. SBD was renamed CSX Transportation (CSX) in 1986. On April 30, 1987, the B&O's corporate existence ended when it was absorbed into the Chesapeake & Ohio Railway, which merged into CSX Transportation on August 31 of that year. 
In railroading's golden age, the B&O was one of several trunk lines uniting the northeast quadrant of the United States into a wide industrial zone. It was the southern border as the New York Central was the northern border. The Pennsylvania Railroad controlled the center, and smaller roads like the Lackawanna, Lehigh Valley, and the Erie in the center surviving largely through the Interstate Commerce Commission. The corners of this map are Baltimore in the southeast, Boston in the northeast, Chicago in the northwest, and St. Louis in the southwest.
|1933||12111||6||(incl in B&O)||(incl in B&O)||(incl in B&O)||(incl in B&O)|
|1933||435||52||(incl in B&O)||(incl in B&O)||(incl in B&O)||(incl in B&O)|
- Mount Airy Branch
The Mount Airy Branch is the surviving, in-use portion of the 1839-opened Mount Airy Loop. The Loop had been mainline track on the Old Main Line until superseded by the Mount Airy Cutoff and Tunnel in 1902.
- Frederick Branch
The Frederick Branch was built from Frederick Junction, on the Old Main Line, to downtown Frederick. The 3.5 mile (5.6 km) branch opened on December 1, 1831. In planning the route of the Old Main Line, the B&O decided against building the main line directly through Frederick, preferring instead to take advantage of a valley grade to the south of the city. :26 The continuation of the main line from Frederick Junction opened April 2, 1832.
- Metropolitan Branch
- Patuxent Branch
The Patuxent Branch was constructed in the 1880s and split off from the Washington Branch at Savage, Maryland to serve a mill, a quarry, and other small industry. After 1925, the line was gradually cut back, and disconnected completely in 2005.
- Georgetown Branch
The Georgetown Branch ran from a junction on the Metropolitan Branch north of the Silver Spring, Maryland station to the Georgetown area of Washington, D.C. Built between 1892 and 1910. Originally intended as an extension of the railroad to a crossing of the Potomac River near the Chain Bridge, the agreement between the Pennsylvania Railroad and the B&O resulting from the rerouting of track for the Washington Union Station project put an end to the crossing, and the branch settled down to being just a country railroad until the Washington, D.C. suburbs grew around it (Silver Spring, Chevy Chase, and Bethesda). The branch was abandoned in 1986, and much of the right-of-way is now used by the Capital Crescent Trail.
- Washington Branch
Original name for the line built between Baltimore and Washington, D.C. during 1833 to 1835. Now called the Capital Subdivision.
- Alexandria Extension
The Alexandria Extension (originally the Alexandria Branch) was built from Hyattsville on the Washington Branch in 1874, ending at Shepherd's Landing. Now connects to the Anacostia Railroad Bridge through Washington, D.C. toward Virginia, serving as a bypass around Washington Union Station for freight trains.
- Washington County Branch
The B&O had decided against a direct line to Hagerstown, though the city had petitioned the Directors. Several north–south routes like the Cumberland Valley built through Hagerstown and the construction of the Western Maryland Railway to that city persuaded the B&O management to build a branch. It was decided that the branch would leave the mainline at Weverton and wind its way through the hills of Western Maryland to Hagerstown. A station was constructed at the stub end of the line in downtown Hagerstown.
- Baltimore & New York Railroad
Constructed from Cranford Junction on the Central Railroad of New Jersey, in Union County, New Jersey, New Jersey east to St. George, Staten Island, New York to give the B&O access to its own deepwater port and ferry terminal. The line no longer runs between Union Avenue and St George on Staten Island. Many attempts have been made to restore it for passenger service, but have hit political, financial, or legal barriers. See entry on Staten Island Railway. More history is at this page.
- Ohio River Branch.
The Marietta & Cincinnati Railroad (M&C), later absorbed into the Baltimore & Ohio Railroad Southwest, included a stretch of track called the Ohio & Mississippi (O&M) that stretched westward from Cincinnati to East St. Louis. "The O&M featured two branches, one south from North Vernon, Indiana to Jeffersonville (Indiana) opposite of Louisville, Kentucky on the Ohio River.(8) The other was from Beardstown, Illinois on the Illinois River to Shawneetown on the Ohio, which crossed the O&M main line at Flora." 
- Category:Baltimore and Ohio Railroad lines
- Category:Stations along Baltimore and Ohio Railroad lines
- Baltimore and Ohio Railroad locomotives
- Baltimore and Ohio Railroad Martinsburg Shops, a National Historic Landmark
- Baltimore Belt Line
- Aeolus Railroad Car
- Camden Station
- Mount Royal Station
- Mount Clare Shops
- Charles T. Hinde
- La Paz, a preserved coach that was operated by B&O
- Jacobs (1989), p. 13.
- An 1827 report shows the motivations of early boosters:
Wooddy, William (1827). "Baltimore and Ohio Railroad. Proceedings of sundry citizens of Baltimore, convented for the Purpose of Devising the most efficient Means of Improving the Intercourse between that City and the Western States". The North American Review. Boston: Frederick T. Gray. 25 (56): 62–73.
- Stover (1987), p. 17 & 75.
- Jacobs (1989), p. 12.
- Moody, John (1919). "Crossing the Appalachian Range". The Railroad Builders, A Chronicle of the Welding of the States. Chronicles of America Series, Vol. 38. New Haven, CT: Yale University Press. Retrieved April 6, 2006.
- Samson, William D. & Previts, Gary John: Reporting for Success: The Baltimore and Ohio Railroad and Management Information, 1827–1856, Business and Economic History, 1999, volume 28, no.2, p.238 
- Lynch, John A. "Justice Douglas, the Chesapeake & Ohio Canal, and Maryland Legal History". University of Baltimore Law Forum. 35 (Spring 2005): 104, 112–125.
- Dilts, James D. (1996). The Great Road: The Building of the Baltimore and Ohio, the Nation's First Railroad, 1828–1853. Palo Alto, CA: Stanford University Press. ISBN 978-0-8047-2629-0.
- "Skerne Railway bridge". Historic England.
- Stover (1987), p. 59–60.
- Stover (1987), p. 2.
- Powell, Bob (December 24, 2014). "December 24, 1852: B&O Railroad completed near Moundsville". West Virginia Public Broadcasting. Archived from the original on July 31, 2015. Retrieved May 19, 2018.
- Fee, Elizabeth (1991). "Evergreen House and the Garrett Family: A Railroad Fortune". In Fee, Elizabeth; Shopes, Linda; Zeidman, Linda. The Baltimore Book: New Views of Local History. Philadelphia: Temple University Press. pp. 11–27. ISBN 0-87722-823-X.
- Hall, C. C. (1912). Baltimore: Its History and Its People. 2. Lewis Historical Publishing Co. pp. 458–461.
- Jacobs (1989), p. 42.
- Jacobs (1989), p. 45.
- Ramage (1999), p. 206.
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- B&O Railroad Historical Society
- B&O Railroad Photo Tours in and around Maryland
- B&O Railroad page on the Baltimore Collective
- Baltimore & Ohio Railroad Museum
- 1827 report shows motivations of early boosters
- John W. Garrett Collection, 1850–1880 Archives Center, National Museum of American History, Smithsonian Institution.
- The Baltimore and Ohio Railroad Network
- Maryland Railroads as of 1850
- Virginia (and West Virginia) Railroads as of 1850
- List and Family Trees of North American Railroads
- B&O Whistles, Whistle museum
- Baltimore and Ohio Rail Road Station From Walnut Street Wharf Schuylkill River, June 29, 1889 by D.J. Kennedy, Historical Society of Pennsylvania