MacKay, John William (1831–1902), miner and businessman, was born in Dublin, son of a Scottish father and an Irish mother. His family were desperately poor, and in 1840 they emigrated to America. Following his arrival in New York, he was educated at a public school but his father died suddenly and he became an apprentice to a shipbuilder, William H. Webb. In 1851 he travelled to California, where he worked as a miner in a number of mines during the gold rush of the 1850s. He moved (1860) to Virginia City, Nevada, and found employment as a ‘timber man’ in a local mine. By this time he had saved a considerable sum of money and decided to finance a mining venture of his own. His first venture ended in failure, but in partnership with J. M. Walker he made a considerable sum from a mine at Gold Hill, Nevada. With Walker he then went into partnership with James C. Flood, William Shoney O'Brien (qv), and James G. Fair (qv), and they worked a series of old workings of the Comstock Lode, convinced that they could mine a large quantity of low-grade ore. After Walker's retirement MacKay owned two-fifths of the company's interest, and in 1865 they obtained the old Hale & Norcross mine, which soon produced a profit of over $500,000. In 1872 he was one of those who discovered the Bonanza mines in the Sierra Nevada, and his company's claim began working a mine known as the ‘Big Bonanza’. They found major workable seams in 1873 and the mine had soon produced over $100 million in both gold and silver. Almost overnight MacKay had become a multi-millionaire, known as ‘the Rocket of the Comstock’; his rags-to-riches story inspired a generation of prospectors to travel to the newly discovered mines. Despite his vast wealth, he continued to supervise the work of his teams and often worked as an ordinary miner at the diggings.
In 1878, in partnership with Flood and Fair, he established the Bank of Nevada, with its headquarters in San Francisco. He became interested in the possibilities of the telegraph and cable business and was determined to end the monopoly built up by Jay Gould. In 1883 he went into partnership with the renowned New York businessman James Gordon Bennett, and established the Commercial Cable Co. They began laying two submarine cables to Europe in 1884 and established a cable station at Waterville, Co. Kerry (1885). Having ended Gould's control of the transatlantic telegraph business, MacKay founded (1886) the Postal Telegraph Cable Co., which soon destroyed Gould's monopoly in mainland America. He also hoped to build up a transpacific cable network, but this project was unfinished at the time of his death.
He remained a devout Roman Catholic throughout his life and was involved in numerous charitable projects, the most notable of which was his financing of an orphanage in Nevada City. In 1885 he was asked to stand as the senatorial candidate for Nevada but declined, and he refused to enter politics on a later occasion. Yet he was not adverse to courting politicians and was an associate of President Ulysses S. Grant during his two troubled presidencies. He later contributed over $25,000 to a special subscription fund for Grant when the former president found himself in straitened circumstances. John McCullough (1832–85), the noted actor, was also his friend, and MacKay supported McCullough in his final illness. He remained in fine physical shape even in his later years, was an admirer and promoter of James J. (‘Gentleman Jim’) Corbett, the famous boxer, and is reputed to have sparred with him.
In February 1895 he survived a bungled assassination attempt while on his way to a business meeting in San Francisco. His would-be assassin was Wesley C. Rippey, a speculator who had lost money in a Utah mine and blamed MacKay, despite the fact that he had no mines in Utah. Rippey approached MacKay from behind and shot him once in the back. Remaining on his feet, MacKay confronted his assailant who, after a number of fumbling attempts, shot himself in the chest. MacKay took a carriage to his hotel where he was operated on by two surgeons. He exhibited the physical toughness that he had developed as a miner and refused to be chloroformed or even to lie down. The surgeons probed the bullet from between his shoulder blades and found that it had narrowly missed his spine. The police later found that the cartridges in Rippey's revolver had been damp and that this accounted for both MacKay's escape and Rippey's failed suicide attempt. They also found that Rippey had a second revolver, with serviceable cartridges, concealed in his coat.
MacKay married (1867) Marie Louise Bryant (née Hungerford), the widow of Dr William C. Bryant. She had one daughter already; they had two sons together. (Their granddaughter, Ellin MacKay, married the songwriter Irving Berlin in 1926.) They lived in Nevada before moving to San Francisco and later to New York. He began to spend an increasing amount of time abroad with his wife, travelling across Europe and also attending society events such as Cowes regatta. In 1885 they leased a house in London near Buckingham Palace. In the same year his stepdaughter married Fernando Colonna, prince of Galatia, a marriage that ended in scandal and divorce. MacKay's expensive lifestyle began to attract an increasing amount of attention in the society papers, and investors responded badly to rumours that he spent lavish amounts on jewellery for his wife. Despite these excesses his fortune was massive and he remained one of the richest men in America. He died in London on 20 July 1902. His remains were returned to New York and buried in a family mausoleum in the Green Wood cemetery, Brooklyn. In June 1908 the University of Nevada dedicated its new school of mining in his honour, located at the university's Reno campus. An impressive statue of MacKay was erected on the mining school's front lawn, depicting him dressed as a miner.