During the Civil War, the railroad route at Mile Post 42 became part of a vital U.S. Army supply line in Middle Tennessee. After Union forces occupied the region in the spring of 1862, Gen. Ulysses S. Grant's officers needed a dependable link between the steamboat dock at Johnsonville on the Tennessee River and the major Union base at Nashville. They took control of the Nashville & Northwestern Railroad and extended the tracks west from Kingston Springs to Johnsonville. Free and enslaved Black men built this military railroad, with about 500 men working on it at a time until the 78-mile line was completed in May 1864. The 12th and 13th U.S. Colored Troops protected it from Confederate cavalry and guerrilla attacks. Its importance increased after Confederate Gen. John Hunt Morgan burned the south tunnel of the Louisville & Nashville Railroad in Sumner County, delaying Federal supplies headed to Nashville. Once completed, the line carried supplies brought by steamboat to Johnsonville, then loaded onto railcars and sent east through this point toward Nashville, Chattanooga, and Atlanta. After the war, Dickson, first called Smeedsville or Sneedsville, grew up along the former military rail line, which remains a reminder of African Americans' significant contributions to Union victory. After the Civil War, Dickson became a railroad hub. Businessman J.T. Halbrook moved there from Centerville in 1899, built the Halbrook Hotel across the tracks in 1913, and the Nashville & Northwestern Railroad built the depot in 1922. Future Tennessee Gov. Frank G. Clement, whose parents worked at and lived in the hotel, was born there on June 2, 1920. The hotel closed in 1954 as automobiles replaced passenger trains in Tennessee, and today it houses the Clement Railroad Hotel Museum with exhibits on Gov. Clement, Middle Tennessee, and Dickson County history.