This thesis focuses on the financial careers of Lionel and Barron Jacobs in Tucson, Arizona, from 1867 to 1913. As early merchants, the Jacobs brothers discovered that cash and credit were scarce in the region, and in 1870 opened a money exchange and lending business. Then in 1879, the Jacobs brothers opened the Pima County Bank to serve the increased economic activity caused by the Tombstone silver discoveries. Mastering the details of banking, they developed management skills and insights. They organized and operated the First National Bank of Tucson (1882-1885), the Bank of Tucson (1885-1887), the Consolidated Bank of Tucson (1887-1890), and the Arizona National Bank (1890-1913). At retirement the Jacobs brothers were among the preeminent financiers of Arizona. A study of their banking experience provides a valuable perspective on the economic growth of southern Arizona during the late nineteenth century and mirrors the problems that bankers faced on remote frontiers.