The Los Angeles office files of H. I. (Horace Ingersoll) Bettis series (1901-1941) contains material relating to the establishment of Las Vegas, Nevada and the Las Vegas Land and Water Company; materials related to the Empire Construction Company that built the San Pedro, Los Angeles, and Salt Lake Railroad line; and financial information and accountancy materials created by the railroad's general auditor, H. I. (Horace Ingersoll) Bettis.

The Arden Station series (1904-1976) consists of materials that detail the operations of the Arden, Nevada train depot between 1907 and 1917, the Union Pacific Railroad, and operations ledgers for the San Pedro, Los Angeles, and Salt Lake Railroad.