The collection consists of the records of a large business conglomerate in northern Mexico founded by Pedro R. Prieto and owned by branches of the Prieto family, including Maíz family members, for three generations: financial and legal documents, maps, business and personal correspondence, and printed materials relating to their mining, urban, and rural properties. Extensive documentation of the mining industry in Mexico before, during, and after the Díaz Era (1876-1911) emphasizes how U.S. investment played an important role. Broad subject coverage focuses on the political and socioeconomic regional history of Mexico during the late 19th and early 20th centuries. The Prieto women demonstrate great acumen in managing the businesses of the Prieto Estate.