Plankinton was born in Allegheny, Pennsylvania, on November 7, 1843.^[2] He was the son of John Plankinton and Elizabeth Bracken Plankinton. While he was still a baby his parents moved to Milwaukee, Wisconsin Territory. He received his early education in the Milwaukee public schools. After graduating from high school, he attended a college in Milwaukee.^[3][4]

Plankinton was employed by his father after he graduated from the Milwaukee college. He soon became a partner in his father's pork and beef packing company. He helped to establish branches in Chicago, Kansas City and New York.^[3] The firm became known in 1893 as the Plankinton Packing Company when the Cudahy brothers moved their operations south to a site just outside of Milwaukee.^[5] Plankinton's main competitors were the meat packing companies of Chicago.^[6]

Plankinton helped found and organize several companies, including the Milwaukee-based Johnson Electric Company.^[7] He founded and was part owner of the Western Portland Cement company in Yankton, South Dakota.^[4] Plankinton held several public offices and was a director of the Milwaukee museum, the city public library, and the Milwaukee industrial exposition.^[4] He was also associated with Layton art gallery and the local Chamber of Commerce.^[8] Plankinton was one of the financial backers of the Postal Telegraph Company that involved telegraph lines in Wisconsin and Michigan.^[9]

Plankinton became vice-president of the Plankinton Bank in 1891 upon his father's death.^[10] He was involved with settling the affairs when the bank failed in 1893.^[11][12][13] The bank crisis involved a scandal of fraud and embezzlement in which Plankinton was implicated.^[14] He was sued to pay back all that was owed to the depositors and creditors.^[15][16][17]

Loans made by the bank to Frank A. Lappen and his companies totaling almost $300,000 precipitated the crisis.^[18][19][20] Lappen was summoned to court to testify about his failure to pay back creditors $750,000, but disappeared to Mexico and could not be extradited.^[21] Philip Danforth Armour, the Chicago meat packer businessman of Armour and Company, was reported to have given $600,000 in gold to help the Plankinton bank pay back those it owed money to.^[22]

On 26 April 1876, he married Mary Ella Woods, of Cincinnati, Ohio, and they had two children.^[3][4] He lived next door to his father in a mansion on Grand Avenue in Milwaukee given to him by his father as a wedding gift.^[23]

Plankinton died in Milwaukee on April 29, 1905.^[4][24] The cause of his death was pneumonia, which he had suffered from for three months prior.^[25][26][27] Plankinton left an estate valued at approximately $4 million to his heirs.^[28][29] His widowed wife received a third and his children split the remainder in equal shares that included the widow.^[30] She died September 7, 1908.^[31]

• Apps, Jerry (17 August 2015). Wisconsin Agriculture: A History. Wisconsin Historical Society Press. ISBN 978-0-87020-725-9.
• Bowman, Francis Favill (1948). Why Wisconsin. F.F. Bowman.
• Buck, James Smith (1886). Milwaukee Under the Charter: Volume 4 – From 1854 to 1860 Inclusive. Milwaukee News Co.
• Buck, James Smith (1890). Pioneer History of Milwaukee.
• Chilton (1905). The Iron Age. Chilton Company.
• Historical Society (1906). Society at Its 34th Annual Meeting Proceedings. State Historical Society of Wisconsin.
• Watrous, Jerome A. (1909). Memoirs of Milwaukee County. Western Historical Association. p. 20.
• West (1918). The Northwestern Reporter. West Publishing Company.
• Wilson, James Grant; Fiske, John; Dick, Charles (1915). Encyclopedia of American Biography. Press Association Compilers.

• Wisconsin in three centuries
• All Things Plankinton