The Lea family was among the largest flour mill operators at the Brandywine Falls, near Wilmington, Delaware, since the 1770s, when Thomas Lea (1757–1823) joined in partnership with Joseph Tatnall (1740–1813) to operate mills on the north bank of the stream. This small collection of Lea family papers documents Delaware and Pennsylvania land use and ownership, elite family and social relationships, and agricultural business operations from the early eighteenth century to the mid-nineteenth century. The materials are from four generations of the William Lea (1805-1876) family lineage. The collection is arranged into four series: Real estate and financial papers, Correspondence, Personal papers, and Newspaper clippings.

The Lea family were among the largest flour mill operators at the Brandywine Fills, near Wilmington, Delaware, beginning in the 1770s until 1927. The mill operated under multiple company names, including Tatnall & Lea, William Lea & Sons, William Lea & Sons Company, Lea Milling Company, and Lea & Company. The records consist of letters, orders, receipts, and advertisements of the William Lea & Sons Company and its predecessors.