When discussing railroads during the Civil War their role is often overlooked. However, they were an incredibly vital and important vehicle in the movement of troops and materiel that ultimately enabled the Union to win the conflict. After fighting broke out between in 1861 the country had a rail network stretching over 30,000 miles. Unfortunately, the South was at an immediate disadvantage in this regard; 21,300 miles (in conjunction with 45,000 miles of telegraph wire), or about 70%, was concentrated in the Northeast and Midwest leaving the Confederacy with only 9,022 miles (and 5,000 miles of telegraph wire). The South did have one important advantage here, much of its trackage was brand new at the start of the war. As William Thomas points out in his book, "The Iron Way: Railroads, The Civil War, And The Making Of Modern America," 75% of its lines were built in the 1850s. Even by the mid-19th century railroads understood the need for heavier rail, reinforced bridges, and durable rights-of-way to handle ever-increasing tonnage. After new routes had been finished they were nearly always rebuilt, sometimes almost immediately, for this purpose.During the war's entire four year history the Confederacy was able to inflict more than $2.5 million in damages to Northern rail lines (over $35 million in today's dollars).
Hope I helped :)