In “Material Classification,” the United States Railroad Administration's Division of Finance meticulously catalogs the materials utilized in railroad operations, encompassing everything from tracks to machinery. This authoritative text employs a precise and technical literary style, reflecting the bureaucratic and operational intricacies of the early 20th-century American rail system. Contextually situated amidst the Post-World War I industrial expansion, this book serves as a critical resource for understanding the classification and management of materials essential to a rapidly evolving transportation infrastructure. The United States Railroad Administration was established during World War I to manage and coordinate the country's rail networks for military efficiency and, subsequently, to oversee peacetime operations. The Division of Finance played a pivotal role in examining the financial ramifications of material resources, thereby influencing procurement strategies and operational efficiency. This expertise stemmed from a need to optimize performance and reduce costs in railway operations during a period marked by substantial growth and technological innovation. “Material Classification” is highly recommended for readers interested in transportation history, industrial finance, or the technical management of railway systems. Its detailed classification systems and insights into early 20th-century logistics offer invaluable perspectives to scholars, historians, and professionals in the fields of transportation and engineering.