In its story of the birth of the machine, The Atlantic spreads the credit around in several different directions, noting "three independent efforts, each of which entered use in 1967: the Bankomat in Sweden, and the Barclaycash and Chubb MD2 in the U.K."
History.com skims past those European efforts to credit to "Don Wetzel, an executive at Docutel, a Dallas company that developed automated baggage-handling equipment," who, it says, "is generally credited as coming up with the idea for the modern ATM." His version, which could do nothing but dispense cash, debuted on September 2, 1969, in New York City.
The Wikipedia entry for the ATM, however, tartly disagrees, saying that "it is widely accepted that the first ATM was put into use by Barclays Bank in its Enfield Town branch in north London, United Kingdom, on 27 June 1967." The entry draws on a delightful BBC profile of "The Man Who Invented the Cash Machine," John Shepherd-Barron, who, while he was in the bath, had a eureka moment.
"It struck me there must be a way I could get my own money, anywhere in the world or the U.K.," Shepherd-Barron tells the BBC. "I hit upon the idea of a chocolate bar dispenser, but replacing chocolate with cash."