the Atlantic, Mississippi & Ohio Railroad combined three railroads to connect Norfolk to Bristol
Source: Library of Congress, A map showing the Atlantic Mississippi & Ohio R.R. and its connections from Norfolk to Cumberland Gap via Bristol (G.W. & C.B. Colton & Co., 1867)
In 1870, the Norfolk and Petersburg, South Side, and Virginia and Tennessee railroads were combined into the Atlantic Mississippi & Ohio Railroad. The mainline linked Bristol to the Chesapeake Bay port of Norfolk, 408 miles away.1
William Mahone negotiated the mergers. He had built the Norfolk and Petersburg prior to becoming a Confederate generate during the Civil War.