he St. Marys Railroad is an 11 mile freight shortline operating in southeast Georgia, connecting the coastal communities of Kingsland and St Marys. Previously anchored by the business from a large paper mill, today the road serves a handful of online customers and offers car storage locations along its right of way parallel to Georgia Route 40. A 4 mile spur track provides occasional rail service to the United States Navy's Kings Bay Submarine Base — home of the Ohio class submarine fleet. Although official interchange is listed in Kingsland with the Genesee & Wyoming shortline First Coast Railroad, in practice the SM runs 13 miles down the former Seaboard Air Line main from Kingsland to the First Coast yard in Yulee, Florida. Here connection is also made with CSX Transportation. St. Marys also hosts scheduled tourist train service conducted by the Florida-Georgia Railway Heritage Museum. Dubbed the Georgia Coastal Railway, these themed trains are based in Kingsland and operate east as far as the St. Marys River.

The 11 mile line was originally constructed by the St. Marys & Kingsland Railroad, incorporated in 1906, but was later renamed the Atlantic, Waycross & Northern Railroad. Interchange was in Kingsland, the last town in Georgia along the Seaboard Air Line. After 1918 and the death of the line's original founder, various companies owned and operated the company: Southern Fertilizer & Chemical, Gillman Paper—St. Marys Kraft, and later Durango Paper. The military spur in use today was laid in 1955 to serve a United States Army ammunition depot, now the site of the Naval Base. When the Durango Paper mill in St. Marys closed in 2002, the future of the shortline was uncertain. In 2007, however, the line was purchased by Boatright Companies in Birmingham, Al, a railroad holding company. Today the line moves more than 1000 carloads annually, with twice that number in railcar storage moves. Maintenance on the railroad's leased power is conducted at a facility in St. Marys; a variety of interesting private railroad equipment is also stored there. Nearby, the former Durango mill footprint is marketed as a potential online industrial site.