The Monongahela Railroad, incorporated on December 31, 1900, was jointly owned by the Pennsylvania and Pittsburgh and Lake Erie railroads to tap the rich coal fields south of Pittsburgh, funneling coal north to its parent roads, which came to include the Baltimore and Ohio in 1926. While many railroads of this size fell victim to bankruptcy or merger in the 1960's and 1970's because of dependence on coal, the Monongahela continued to thrive and grow as split ownership ensured its independence and rising demand for high BTU, medium-sulfur coal brought prosperity. In 1984, a 15-mile branch line was built to serve Consolidated Coal Company's new Bailey Mine, then the largest underground mine in the country, and the 177-mile railroad became the nation's seventh largest coal-hauling railroad. In 1993, the P&LE and CSX Transportation, successor to the B&O, sold their interests and the Monongahela was wholly merged into Conrail. Caboose No. 67 was one of ten new NE-6 cabooses purchased from the International Car and Equipment Company of Chicago in September 1949 after the railroad had previously relied on cars from its parent lines. Used on the tail end of trains for safe operation, it gave the conductor or brakeman a place to watch the train as well as office and living space for the crew, and it often ran at the front on return trips from coal mines where there were no tracks to run the locomotive around the train. In the late 1960's, No. 67 struck a coal truck at a grade crossing, probably leading to the addition of an air whistle on the roof of the cupola. As cabooses rapidly disappeared from regular service in the 1980's, the Monongahela refurbished and donated No. 67 in 1989 for long-term display in Strasburg.