Created on March 4, 1785, from part of Lancaster County, and named for the Dauphin, the title of nobility given to the eldest sons of kings of France. Harrisburg, the county seat, was named for its founder, John Harris, and was incorporated as a borough on April 13, 1791. It was chartered as a city on March 19, 1860.

     John Harris’s trading post stood on the Susquehanna as early as 1720. Presbyterian groups at Paxton and Manada Gap were the earliest settlers, but German Lutherans formed the Hummelstown and Middletown communities in the 1760s. The Paxton Boys movement of 1763–1764 slaughtered helpless Indians and tried to intimidate the provincial government into providing more defense on the frontier and more legislative representation. The State’s capitol was moved from Lancaster to Harrisburg in 1812, and the next year Lebanon County was created from Dauphin’s eastern townships. In the mid-nineteenth century Dauphin was a canal and railroad center. Later, steel mills went up in Steelton. In Middletown, American Tube and Iron Co. flourished, and railroad cars were made there. Today, Milton Hershey’s industrial legacy is still apparent and AMP is a national leader. Thirty percent of the land is farmed, and this is a leading county in sheep and poultry. In total value its farm products rank twenty-fifth among the state’s sixty-seven counties.