The Blue Ridge Tunnel: 4,273 feet through hard rock

Construction of the Blue Ridge Tunnel began in 1850 and ran for eight years. The bore was 4,273 feet long, making it the longest railroad tunnel in North America when it opened.

Crozet's correspondence between 1849 and 1858 contains the phrase "hard rock" some ninety times. The tools were hand drills, pickaxes, and volatile black powder, in an era a decade before dynamite. The work proceeded from both ends of the bore simultaneously.

The two bores met on December 29, 1856, with an alignment error of less than six inches over more than four thousand feet of horizontal distance through mountain rock. The first train passed on April 13, 1858. The tunnel served the Virginia Central Railroad and its successor the Chesapeake and Ohio (the C&O) until 1944, when a parallel lower-elevation bore replaced it.