Archaeological research of a railroad, although not dissimilar to researching the history of a place, has unique aspects that make it challenging for those not familiar with the subject. Four words are vital to understanding a railroad: economics, operations, infrastructure, and regulation. With exceptions, a railroad in the United States exists only with all four in place. An archaeologist should investigate each to complete a holistic picture, although each may not always be essential for complete understanding of a particular railroad project. The author briefly discusses these issues and then identifies types of relevant historical documents and select archaeological features important in understanding a railroad. A case study of Lampo, a Central Pacific Railroad section station operative from the 1880s to 1942, is included to highlight important links between document research, archaeology, and the key operative aspects of a railroad.