Hugo Walter Miller was a businessman and engineer in Nogales, AZ. He began Miller's Assay Office in 1913 which later became Miller and Cox from 1921 to 1924, and finally as Hugo W. Miller Assay Office from 1924 to 1958.

 The collection includes assay and ore records, and miscellaneous financial and administrative papers. Also included are mill, smelter, and convertor reports for the Pride of the West Mining and Milling Company for 1902.