Active house
Cargill-MacMillan family
Cargill · United States · founded 1865
Owners of Cargill, the largest privately held company in the United States by revenue.
Family fortune
$60B
Bloomberg Family Index, as of 2025-12-31
Generations
6
Documented members
4
Industries
Agriculture, Commodities
Founders, principals and heirs
William Wallace Cargill
Founder · generation 1 · 1844–1909
Opened a grain warehouse in Iowa in 1865.
John H. MacMillan Sr.
Principal · generation 2 · 1869–1944
Led the company through its expansion.
Whitney MacMillan
Principal · generation 4 · 1929–2020
Last family member to serve as CEO.
Gwendolyn Sontheim Meyer
Heir · generation 5 · 1958–
Shareholder and philanthropist.
Legacy
Roughly 90% of the company is still held by around two dozen family members.
Evidentiary standard
Family fortunes are only recorded where a named wealth desk publishes a standing family-level estimate; the source and valuation date are shown with the figure. Houses whose assets are held through charitable trusts, foundations, or sovereign vehicles carry no figure, because no verifiable personal total exists. Lineage entries are limited to publicly documented family members.