Alaska Railroad No. 557 is an S-160 class 2-8-0 "Consolidation" type steam locomotive built by the Baldwin Locomotive Works of Philadelphia, PA in December 1944, originally for the U.S. Army Transportation Corps (USATC) as their No. 3523. It is one of several S-160 class 2-8-0 type locomotives built by Baldwin, ALCO, and Lima for the U.S. Army between 1942 and 1945 for use in Europe and Africa during World War II. It would later be sold in 1945 to the Alaska Railroad along with eleven others of this locomotive type and was renumbered to 557. It was later converted to burn oil when the federally-owned Alaska Railroad retired all of its other coal-burning steamers in 1954.
It was the last steamer in regular service in Alaska, kept primarily to help during high-water conditions in Nenana, where the Tanana and Nenana Rivers regularly flooded the entire town and railyard. Diesel traction motors at the time did not perform well in water, whereas steam-powered locomotives could easily handle two feet of water over the rails. It continued in occasional service for special events such as the annual fair trains and excursions.
It was retired from regular service in June 1963 and later sold in 1964 to the Michaelson Steel & Supply Company in Everett, WA for scrap. However, it was then sold to Monte Holm of Moses Lake, WA and displayed in his House of Poverty Museum where it was relettered for the Mon-Road Railroad. After Holm's death in 2006, Jim and Vic Jansen bought 557 from the museum and returned it to the Alaska Railroad on the condition that it be restored.
In 2011, the Alaska Railroad reacquired the locomotive for restoration to operating condition for use on special excursions between Anchorage and Portage, AK. It was contributed in August 2012 to the non-profit Engine 557 Restoration Company in Wasilla, AK where the restoration process is slowly taking shape. In 2015, several operational components were removed from its sister locomotive, Alaska Railroad 2-8-0 No. 556, to aid in the restoration process. Since 556 is only on static display, all of its removed components were replaced with replicas.
As of mid-2024, the rebuilt boiler has passed a formal hydrostatic test witnessed by the Federal Railroad Administration (FRA) and the restoration is nearing completion. The locomotive is scheduled to undergo steam tests in late 2024 and to be back on the rails under its own steam power for excursion service sometime in 2025.