Nineteenth century US railroads were the first ‘big businesses’ and had profound influence on society. This paper addresses one source of talent for the early US public accounting profession—railroads. Following the end of the US Civil War (1861–65), industrial expansion was a revolutionary experience, with large trusts appearing in the wake of the railroad's maturing influence on the development of a vast continental economy. Accounting practice also was impacted by railroads. For example, the development of annual reports, income measurement, the standardization of reporting by regulators, developing fixed and variable cost, and throughput concepts for capital intensive business—all were related to the railroads. This paper focuses on a significant link between the emerging public accounting profession and the railroads by examining how an early major US public accounting firm relied upon accounting skill developed within railroads as an important source of talent. Arguably, talent is the most important resource of a professional firm. While it is a commonly held view that the immigration of UK accountants in the late nineteenth century was the source of public accounting talent, this paper provides evidence of a competing explanation—the sourcing of talent from a firm (Haskins & Sells) that continues to the present day as Deloitte. Key leadership and personnel of that time gained their experience while working on the domestic railroads.