During the initial years of electricity distribution, Edison's direct current was the standard for the United States and Edison was not disposed to lose all his patent royalties. From his work with rotary magnetic fieldss, Tesla devised the system for transmission of power over long distances. He partnered with George Westinghouse to commercialize this system. Westinghouse had previously bought the rights to Tesla's polyphase patents and other patents for AC transformers.
Experts announced proposals to harness the Niagara Falls for generating electricity. Against General Electric and Edison's proposal, Tesla's AC system won the international Niagara Falls Commission contract. The commission was lead by Lord Kelvin and backed by entrepreneurs such as J.P. Morgan, Lord Rothschild, and John Jacob Astor. Work began in 1893 on the Niagara Falls generation project and Tesla's technology was applied to generate electromagnetic energy from the falls.
Edison went on to carry out a campign to discourage the use of alternating currents, what today would be commonly referred to as FUD. Edison did preside personally over several executions of animals, primarily stray cats and dogs, for the benefit of the press to prove that his inferior system of direct current was safer than that of alternating current. Edison's series of animal executions peaked with the electrocution of Topsy the Elephant. Ironically Edison was against capital punishment, but his desire to disparage the superior system of alternating current led to the invention of one of the world's most recognizable killing devices.
Adversaries due to Edison's promotion of DC for electric power distribution over the more efficient alternating current advocated by Tesla, Edison (or, reportedly, one of his employees) employed the tactics of misusing Tesla's patents to construct the first electric chair for the state of New York in order to promote the idea that alternating current was deadly. Popular myth has it that Edison invented the electric chair, despite being against capital punishment, solely as a means of impressing the public that alternating current was more dangerous than direct current, and would therefore be the logical choice for electrocutions. In fact, the chair was primarily invented by a few of his employees, in particular Harold P. Brown, working at Menlo Park (though Edison certainly monitored their operations). 
Some doubted that the system would generate enough electricity to power industry in Buffalo. Tesla was sure it would work, saying that Niagara Falls had the ability to power the entire eastern U.S. On November 16, 1896, the first transmission of electrical power between two cities was sent from Niagara Falls to industries in Buffalo from the first commercial two-phase power plants (known as hydroelectric generators) at the Edward Dean Adams Station. The hydroelectric generatorss were built by Westinghouse Electric Corporation from Tesla's AC system patent designs. Tesla's system designs alleviated the limitations of the previous DC methods. The nameplates on the generators bear Tesla's name. He also set the 60 hertz standard for North America. It took five years to complete the whole facility.
Edison's inventions using direct current ultimately lost to alternating current devices proposed by others: primarily Tesla's polyphase systems and other contributors, such as Charles Proteus Steinmetz (of General Electric). With the financial backing of George Westinghouse, Tesla's AC replaced DC, enormously extending the range and improving the safety and efficiency of power distribution. Tesla's Niagara Falls system marked the end of Edison's roadmap for electrical transmission. Eventually, Edison's GE company converted to the AC system.