P.S. du Pont (1870-1954) and Louise (du Pont) Crowninshield (1877-1958) were second counsins.

Pierre Samuel "P.S." du Pont (1870-1954) was an industrialist, entrepreneur, and philanthropist. He was president of E.I. du Pont de Nemours & Co. from 1915 to 1919 and chairman of the board from 1919 to 1940. P.S. du Pont was the great grandson of Eleuthere Irenee du Pont (1771-1834), founder of E.I. du Pont de Nemours & Company, and the great-great-grandson and namesake of the French economist, Pierre Samuel du Pont de Nemours (1739-1817).

Born in 1870, P.S. du Pont was the third child and eldest son of Mary Belin (1839-1913) and Lammot du Pont (1831-1884). P.S. du Pont had ten siblings; four brothers and six sisters, two of whom died at a young age. The patriarch of the family, Lammot du Pont was a chemist and the inventor of B blasting powder, using Chilean sodium nitrate instead of the previously used potassium nitrate (saltpeter) from India. In 1879, Lammot du Pont resigned from the DuPont Company and formed the Repauno Chemical Company to manufacture high explosives. The family moved from the Brandywine to Philadelphia and lived at 3500 Powelton Avenue. Lammot du Pont died in an explosion on March 29, 1884. In 1892, Mary Belin du Pont had a family home built called Saint Amour in Wilmington, Delaware.

du Pont graduated from the Massachusetts Institute of Technology in 1890 and became assistant superintendent of the du Pont Company's black powder mills in Delaware. In 1901, he hired John J. Raskob (1879-1950) as his personal secretary. du Pont had met Raskob while managing and later overseeing the liquidation of the Johnson Company in Lorain, Ohio.

In 1902, he worked with two cousins, T. Coleman du Pont (1863-1930) and Alfred I. du Pont (1864-1935), to reorganize the du Pont Company. With T. Coleman as president, Pierre became vice president, treasurer, and assistant secretary. As a member of the finance committee, he played a pivotal role in reorganizing the company into a large, modern corporation. In 1915, P.S. du Pont purchased T. Coleman du Pont's stock and became president of the company. He was also elected director of the General Motors Company, which at the time was near bankruptcy. Working with Alfred Sloan (1875-1966), he reorganized the company and in 1920 replaced William C. Durant (1861-1947) as president.

Early in 1906, a lumber mill was intending on cutting down several hundred acres of trees in Kennett Square, Pennsylvania. This prompted du Pont to purchase 200 acres of former farmland with the intention of saving the trees. The farm had belonged to five generations of the Peirce family before falling into disrepair and off to a non-familial ownership. In 1914, du Pont completed the Peirce-du Pont house or Longwood Mansion. In 1919, construction began on the main conservatory. Over time, du Pont drew on his interest in horticulture and developed several different types of gardens, greenhouses, fountains, a ballroom, music room, an organ, and a theater. du Pont and his wife Alice Belin du Pont (1872-1944) hosted many garden parties, family affairs, and events for several organizations. Prior to his death in 1954, du Pont established a foundation for the arboretum and botanical gardens, Longwood Gardens. Longwood Gardens is open to the public and attracts over 1 million visitors per year.

Along with an active business career, du Pont was involved in social issues and philanthropic concerns. In the 1920s he was a pivotal member of the Association Against the Prohibition Amendment. In the years between 1934 and 1941, he was a member of the American Liberty League. du Pont was also concerned with issues in his native state of Delaware; these included improving African-American education and building better roads, especially on Kennett Pike.

P.S. du Pont, married Alice Belin (1872-1944) in 1915, died without issue in 1954.

Louise Evelina du Pont(1877-1958) was the daughter of Henry A. du Pont (1838-1926) and Pauline Foster du Pont (1849-1902). She was born, raised, and educated at the family estate, Winterthur, north of Wilmington, Delaware. A debutante whose coming-out party was held in New York in 1896, she socialized with members of the city's most exclusive families. During the late 1890s, she spent the winter months in the city, enjoying shopping and social life during the heyday of high society. Louise du Pont was also interested in charitable causes and in 1897 organized "Willing Helpers," a group of young women which met Saturday mornings to make clothing for babies at a Wilmington day nursery; she headed this group for three years.

In 1900, Louise du Pont married Francis Boardman Crowninshield (1869-1950), a renowned sportsman who raced yachts and was a expert marksman. There were no children by this marriage. The Crowninshields had homes in Marblehead and Boston, Massachusetts; Boca Grande, Florida; and the original du Pont family estate, Eleutherian Mills, north of Wilmington, Delaware.

Louise du Pont Crowninshield actively participated in charitable organizations, horticulture, historic preservation, and collected antiques and hooked rugs. One of her earliest historic restoration projects was the original du Pont family estate; Eleutherian Mills, where she resided during the spring and fall months. With her husband's eye for architectural detail, and Crowninshield's love of nature, tegether, they developed a garden on the ruins of the Saltpetre Refinery which stood between Eleutherian Mills and the Brandywine River.

Crowninshield was a founding trustee of the National Trust for Historic Preservation in 1949 and was vice-chairman of the board in 1953. In 1955, President Dwight D. Eisenhower (1890-1969) appointed her to the Boston National Historic Sites Commission. She was also involved with historic restoration in Virginia, particularly the Kenmore Association, of which she was a regent, (Kenmore was the Fredericksburg, Virginia, home of Fielding Lewis (1725-1781) and his wife, Betty Washington Lewis (1733-1797), George Washington's sister). She often provided financial assistance and artifacts when needed at historic sites. In addition, she was a member or trustee of numerous historical societies, museums, art, and symphony organizations. Crowninshield's additional interests included travel and her pet dogs.