The Scottish origins of the Hepburn family can be traced as far back as the year 1200. Tradition suggests that the surname is the combination of the names of two rivers, evolving from Hebron to Heborn to Hepborn and finally the modern variant Hepburn. This text presents the genealogies of the brothers James and William Hepburn, who immigrated to Pennsylvania from Donegal, Ireland in 1773. The genealogies follow the male line from Samuel Hepburn (b. 1698, Glasgow, Scotland) up to the 1890s and are enhanced by a wealth of biographical material. Several portraits and a full-name index enhance the text. James and William were two of four sons born to Samuel while living in Donegal, Ireland. The Hepburns had fled Scotland to avoid religious persecution and were intrigued by favorable reports from settlers in the thirteen colonies. In 1773, Samuel sent his two oldest sons to Pennsylvania to see if the rumors of financial opportunity were true. This voyage firmly established the Hepburns in both Philadelphia and the Susquehanna Valley. Within ten years the elder Samuel and Samuel Jr. would follow James and William to the new world, settling in Philadelphia. The fourth son, John, was lost at sea with his mother and sister c.1775, at either New Foundland or the New Jersey coast. James made a name for himself as a successful merchant and broker of land. William was a renowned militiaman, served on the State Senate, and was instrumental in the formation of Lycoming County, Pennsylvania, in 1795. Both were key players in the establishment of the city of Williamsport.