Early in adulthood, Donner managed the family-owned grain mill, and in his twenties, he invested in Indiana natural gas and real estate. He founded the National Tin Plate Company, originally based in North Anderson, Indiana, and obtained a patent for an innovation in tin plate rolling processes.
Donner then shifted his energies from Indiana to the Monongahela Valley of southwestern Pennsylvania. In 1897, his National Tin Plate Company was the first employer in the newly created community of Monessen, Pennsylvania, and the town's main street was named "Donner Avenue" in his honor.
Donner then sold his tin plate company, and used the proceeds to create Union Steel Company (later American Steel and Wire Company), located in the new community of Donora, Pennsylvania, in 1899-1900. The "Don" in "Donora" was in recognition of William Donner's key role in the founding of that community. In creating Union Steel Company, Donner received financial backing from Henry Clay Frick, Andrew W. Mellon, and Richard B. Mellon, in addition to Donner's own funds. The town was the site of the Donora Smog of 1948.
After selling his Donora-based company in 1903, Donner became President of Cambria Steel Company, and also served as Chairman of the Board of the Pennsylvania Steel Company. Near the end of his career, he created the Buffalo-based Donner Steel Company, which he sold in 1929.
In 1914, a new cargo ship (at 524 feet long and 9,600 tons one of the largest on the Great Lakes at the time), the William H. Donner was named in his honor at the Great Lakes Engineering Works and shipyard in Ashtabula, Ohio. Still holding the name, it had functioned since 1969 as a stationary crane ship and cargo transfer hull in Marinette, Wisconsin. It was owned by K.K. Integrated Logistics. Her final retirement came in 2015, and as of March, 2016, the 102 year-old vessel had been moved and is now in the Menominee river on the Michigan side awaiting scrapping. The ship's pilot house and superstructure had been removed several years earlier.
Donner's son, Joseph, died in 1929, from cancer. In 1932, Donner turned his attention to philanthropy, with a special interest in cancer research. He founded two notable foundations that are still in operation today, the William H. Donner Foundation in the United States, and the Donner Canadian Foundation in Canada. William H. Donner died in Montreal in 1953.
After his death
In 1958, the William H. Donner Foundation used $2.5 million to fund five chairs in science at MIT, Harvard, Yale, Princeton and the University of Pennsylvania thus creating the title of Donner Professor.
The Donner Canadian Foundation was established in 1950 and for 43 years was a typical, uncontroversial Canadian charitable fund. In 1993, the conservative American Donner heirs who control the foundation changed its primary focus to that of supporting conservative research.
From 1993-99, under the leadership of executive directors Devon Gaffney Cross and then Patrick Luciani, the foundation provided the seed money to start several conservative Canadian think-tanks and publications, and became the "lifeblood of conservative research" in Canada.
In 1999, the American Donner heirs who control the foundation began donating more of its money to land and wildlife conservation, international development, medical research and the arts, reducing funding of conservative research (though it is still one of the most generous benefactors to the right in Canada).
- "About William H. Donner". The William H. Donner Foundation, Inc. Retrieved 2008-07-30.
- Vivian, Cassandra (2002). Monessen: A Typical Steel Country Town. Charleston, South Carolina: Arcadia Publishing. p. 14. ISBN 0-7385-2383-6.
- MIT receives $500,000 grant from the Donner Foundation, The Tech, May 23, 1958
- Walkom, Thomas (October 1997). "Right-wing causes find a rich and ready paymaster. Canada 'too liberal', so Donner family is taking foundation down a more controversial path". Toronto Star. pp. E1.
- Cernetig, Miro (February 1994). "Neo-cons young bucks of the new right. In the 1960s the rallying cry for young activists was free love. Now it's free markets". The Globe and Mail.
- Camp, Dalton (February 1997). "Politics, journalism of new right fueled by money". Toronto Star. pp. A19.
- Daifallah, Adam (November 2004). "Rescuing Canada's right". Western Standard.