Baltimore & Ohio B&O

The Baltimore and Ohio Railroad (B&O or BO) was the first common carrier railroad and is also the oldest in the United States, having opened in 1830. Initially, the railroad served the trade needs of stores in Baltimore, and it was originally confined to Maryland.

Faced with competition from the Chesapeake and Ohio C&O Canal, the B&O constructed a bridge across the Potomac River at Harpers Ferry, Virginia. The line then extended from Virginia, following the North Branch of the Potomac River, and eventually re-entered Maryland on its route to Cumberland. The railroad played a key role in the Union Army's success during the Civil War.

Eventually, the B&O lines were integrated into the CSX Transportation Network.