Norfolk Southern Railway's history in southeastern Virginia began in the mid-19th century when a young civil engineer named William Mahone designed an innovative 12-mile-long roadbed through the Great Dismal Swamp that is still in use today. Trees were felled and laid side by side at right angles beneath the swamp's surface, forming a corduroy road, with the roadbed built on top of the logs. The logs sank into the boggy swamp, where they were preserved. Nearly 170 years later, Mahone's corduroy design continues to serve as a major route for Norfolk Southern traffic, supporting millions of tons of freight each year as the railroad provides extensive service throughout Hampton Roads. One of the nation's largest Class 1 railroads, Norfolk Southern was created through the merger of Roanoke-based Norfolk & Western Railway and Washington, DC-based Southern Railway in June 1982.