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War of the currents: Westinghouse and Tesla vs Edison
c. 1886–1893· Event· Innovations & industries
Well documentedSolid records, texts or physical evidence.
A late-1880s battle between Edison's direct current and Westinghouse's alternating current over the standard for electric power.
See it on the Innovation & Wealth map →What happened
Edison's direct current (DC) could reach only about a mile from a power station. Alternating current (AC), using transformers to step voltage up and down, could carry power for miles. Westinghouse backed AC from 1886 and licensed Tesla's AC motor in 1888. Edison's side warned AC was deadly; ally Harold Brown electrocuted animals in public, and New York's first electric-chair execution, in 1890, used Westinghouse generators. Westinghouse won the 1893 Chicago World's Fair lighting and Niagara Falls generator contracts.
Impact on society and the economy
AC became the world standard, letting large, distant power plants serve whole cities and regions. Ironically, high-voltage DC now carries some long-distance power.
Think of it like
Like a format war over building standards: the system that scales across a whole region wins, even if the incumbent got there first.
How we know
Patents, company records, newspaper coverage, the Edison company's 1888 pamphlet 'A Warning' attacking AC, and records of the 1890 Kemmler execution and the Niagara contracts.
Still debated
Letters published in 1889 showed Edison's company aided Brown; how much Edison personally directed the scare campaign is debated.
Connections (3)
▸Thomas Edison and General Electric backed DC and lost War of the currents: Westinghouse and Tesla vs EdisonWell documented
The connection
Edison had built his business on direct current, with power stations, patents and royalties tied to it. Rather than switch, he attacked AC as deadly. But investors, including Morgan's bank, saw AC's advantages; in 1892 they merged Edison General Electric with Thomson-Houston into GE, which sold AC.
When and how
New York and New Jersey, 1887–92: the Edison company's 1888 'Warning' pamphlet, the 1890 electric chair, and the 1892 merger forming GE.
How we know
Company pamphlets, letters, newspaper coverage and merger records document Edison's stance and his loss of control; he sold most of his GE shares.
Debates
Was his opposition genuine safety concern, since early AC lines did kill linemen, or protection of his DC investments? Probably both, in proportions still argued.
▸Nikola Tesla supplied key AC patents for War of the currents: Westinghouse and Tesla vs EdisonWell documented
The connection
Early AC systems could light lamps but lacked a practical motor, a big gap since factories wanted power for machines. Tesla's 1888 polyphase induction motor, driven by a rotating magnetic field, filled it. Westinghouse bought the patents, and Tesla's polyphase design became the basis of the Niagara Falls power system.
When and how
New York, 1887–88 (patents and Tesla's May 1888 lecture to the American Institute of Electrical Engineers); Pittsburgh, 1888–89; Niagara Falls, 1895.
How we know
The patents, Tesla's published lecture and Westinghouse licensing contracts survive; Niagara's generators used his polyphase system.
Debates
Italian physicist Galileo Ferraris described a rotating-field motor at about the same time, and others supplied key AC parts, so Tesla's share of credit is debated.
▸George Westinghouse led the winning AC side in War of the currents: Westinghouse and Tesla vs EdisonWell documented
The connection
Westinghouse saw that AC, stepped up by transformers, could carry power far beyond DC's one-mile reach. He bought transformer rights, built AC systems from 1886 and licensed Tesla's motor, then won by underbidding GE to light the 1893 Chicago World's Fair and securing the Niagara Falls generator contract.
When and how
Pittsburgh and Great Barrington, Massachusetts (William Stanley's 1886 AC demonstration); Chicago, 1893; Niagara Falls, 1893–96.
How we know
Contracts, fair records, Niagara power company records and press reports document his firm's victories; by the late 1890s AC dominated new US installations.
Debates
Would AC have won anyway, through GE or European firms such as Siemens and Ganz, without Westinghouse's costly gamble? It is an open counterfactual.