Cargill, MacMillan Families

Estimated Net Worth: $42.9 billion

Sixth-generation Cargill and MacMillan family members oversee Cargill Inc., among the largest closely held companies in the U.S. Cargill is a commodities giant that began in Iowa more than 150 years ago. With operations spanning industrial, agriculture and food products and services, the company is now based in Minneapolis.

W.W. Cargill founded Cargill Inc. back in 1865 as a small grain storage company. Today the agro-giant is the largest private company in the world, with nearly $120 billion in revenue and 130,000 employees in 63 countries.

The secretive Cargill family still owns 88% of the company, but the wealth has passed down through three and four generations now. Part went to W.W.'s son Austen, whose two children both died in 2006. Margaret, Austen's daughter, gave her one-sixth share of the company to charity. James, Austen's son, passed his wealth on to his three children: James Cargill, Austen Cargill, and Marianne Liebmann each own one-eighteenth of the family share and thus are ongoing members of The Forbes 400. WhitneyHe sold his 50,000-acre Montana ranch in May 2016 for an undisclosed sum. The ranch, which was listed for $21.5 million, once hosted Lewis and Clark.

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The other side of the family comes from the children of W.W.'s daughter, Edna (who married John MacMillan). Her son Cargill MacMillan Sr. died in 1968. His three children, Whitney MacMillan, Cargill MacMillan, and Pauline MacMillan Keinath are also members of the Forbes 400, with one-ninth of the family share each. Meanwhile, Cargill Sr.'s brother John MacMillan Jr. had three children: Marion, John and Whitney. Marion MacMillan Pictet retains one-ninth and makes the list with her cousins. Her two brothers, John Hugh and Whitney Duncan, died in 2008 and 2006, respectively. Their children each own further fragmented pieces of the family fortune.