Bourbon whiskey was named after Bourbon County because of the quantity and quality of whiskey produced within its borders. It is made from a fermented mash of at least 51% corn, with less wheat, rye, or barley, yeast, and limestone water, distilled at no more than 160 proof, and aged in charred oak barrels. In 1964, Congress recognized bourbon as a distinctly American product. Jacob Spears, a Pennsylvanian who settled in Paris, was an innovative farmer and one of the first distillers of bourbon whiskey. His Stone Castle, built in 1790 by Thomas Metcalfe, stands 1 mile south, and a springhouse and storehouse for his bourbon whiskey still stand on the farm as the most complete distiller's complex in existence today.