Near Wilmington, Delaware, Hagley Museum and Library preserves the original Brandywine site where Éleuthère Irénée du Pont founded black powder mills in 1802 after buying the property in 1801. Chosen for water power, raw materials, transportation, and building stone, the mills grew into the world’s largest black powder works before production ended in 1921. The site later became a nonprofit institution with a museum, library, restored mills, workers’ community, family home, and garden that connect early American industry with family and working life. Its research collections on American business and technology have also made it an important center for studying industrial history.