Western Maryland Scenic Railroad No. 734, also known as Mountain Thunder, is an SC-1 class 2-8-0 “Consolidation” type steam locomotive originally built by the Baldwin Locomotive Works in 1916 for the Lake Superior and Ishpeming Railroad (LS&I) as No. 18. It was renumbered to 34 in 1925. No. 34 was used to pull heavy iron ore trains for the LS&I, until it was retired in 1961. The locomotive was subsequently sold to the Marquette and Huron Mountain Railroad, where it was stored in a sideline alongside other LS&I steam locomotives. In 1971, No. 34 was sold to the Illinois Railway Museum for static display.

Baldwin Locomotive Works (BLW) was an American manufacturer of railway locomotives from 1825 to 1951. Originally located in Philadelphia, Pennsylvania, it moved to nearby Eddystone in the early 20th century. The company was for decades the world's largest producer of steam locomotives, but struggled to compete when demand switched to diesel locomotives. Baldwin produced the last of its 70,000-plus locomotives in 1951, before merging with the Lima-Hamilton Corporation on September 11, 1951, to form the Baldwin-Lima-Hamilton Corporation.