Expansions
The building of the railroad began on July 4, 1828. A route was laid out to follow the Patapsco and Monocacy rivers to the Potomac. The line was opened for service to Ellicott's Mills on May 24, 1830. On December 1, 1831 the the rail was opened to Frederick. The B&O opened a branch from Relay, Maryland to Washington in August 1835, crossing the Patapsco River on the Thomas Viaduct. Two years later a bridge was completed across the Potomac to Harpers Ferry, West Virginia. At Harpers Ferry, the B&O connected with the Winchester & Potomac Railroad, forming the first conjunction of two railroads in the U.S. The line continued through Cumberland, Maryland to Grafton, West Virginia, where it turned northwest to reach its goal at Wheeling, West Virginia on January 1, 1853. Another line was pushed from Grafton to reach the Ohio River at Parkersburg, West Virginia in 1856. After the Civil War the B&O continued west in 1866 by leasing the Central Ohio Railroad, a line from Bellaire, Ohio, across the Ohio River from Wheeling, through Newark to Columbus, and in 1869 by leasing a line from Newark to Sandusky, Ohio. From a point on that line called Chicago Junction a subsidiary company, the Baltimore & Ohio & Chicago, built west to Chicago between 1872 and 1874. In 1871 the Pittsburgh & Connellsville Railroad completed a line from Cumberland to Pittsburgh and leased it to the B&O. B&O opened a new line from Baltimore to Philadelphia in 1886. When Charles F. Mayer became president of B&O, he made many improvements to the railroad. He got control of the Pittsburgh & Western Railroad, constructed a line from Akron, Ohio to Chicago Junction, gained control of a route from Parkersburg, West Virginia through Cincinnati to St. Louis, construction of a line through, around and under Baltimore to connect the Philadelphia route with the rest of the B&O, and electrification of the Baltimore Belt, the first mainline electrification in North America. Daniel Willard then became president and also made many expansions of the railroad. This included the purchase in 1910 of the Chicago Terminal Transfer Railroad, the acquisition in 1917 of the Coal & Coke Railway from Elkins to Charleston, West Virginia, and the acquisition of portions of the Cincinnati, Hamilton & Dayton Railway and its leased lines to form a route from Cincinnati to Toledo. In 1926 B&O purchased the Cincinnati, Indianapolis & Western Railroad's line from Hamilton, Ohio to Springfield, Illinois.In 1927 B&O began to purchase Western Maryland Railway (WM) stock. In 1929 the B&O bought the Chicago & Alton, reorganized it as the Alton Railroad, and operated it as part of the B&O. In 1932 B&O acquired the Buffalo, Rochester & Pittsburgh Railway and also purchased the Buffalo & Susquehanna Railroad. In 1934 B&O arranged for track rights on the Pittsburgh & Lake Erie's Railroad's water-level route between McKeesport and New Castle, Pennsylvania. In 1981 B&O leased the former Rock Island route Blue Island to Henry, Illinois.