In the earliest days of telephone technology, prior to the development of the rotary dial telephone, all telephone calls were operator-assisted. To place a call, the caller was required to pick up the telephone receiver, sometimes turn a magneto crank, and wait for the telephone operator to answer. The caller would then ask to be connected to the number they wished to call, and the operator would make the required connection manually, by means of a switchboard. In an emergency, the caller might simply say "Get me the police", "I want to report a fire", or "I need an ambulance or doctor". Until dial service came into use, one could not place calls without proper operator assistance.
The first known use of a national emergency telephone number began in the United Kingdom in 1937-1938 using the number 999, which continues to this day. In the United States, the push for the development of a nationwide American emergency telephone number came in 1957 when the National Association of Fire Chiefs recommended that a single number be used for reporting fires. The first city in North America to use a central emergency number was the Canadian city of Winnipeg, Manitoba in 1959, which instituted the change at the urging of Stephen Juba, mayor of Winnipeg at the time. Winnipeg initially used 999 as the emergency number, but switched numbers when 9-1-1 was proposed by the United States. In 1967, the President's Commission on Law Enforcement and Administration of Justice recommended the creation of a single number that could be used nationwide for reporting emergencies. The Federal Communications Commission then met with AT&T in November 1967 in order to choose the number.
In 1968, the number was agreed upon. AT&T chose the number 9-1-1, which was simple, easy to remember, dialed easily, and because of the middle 1, indicating a special number (see also 4-1-1 and 6-1-1), worked well with the phone systems in place at the time (which 999 would not). At the time, this announcement only affected the Bell System telephone companies; independent phone companies were not included in the emergency telephone plan. However, Bob Gallagher of the Alabama Telephone Company decided he wanted to implement it ahead of AT&T, and the company chose Haleyville, Alabama, as the location.
On February 16, 1968, Alabama Speaker of the House Rankin Fite placed the first-ever 9-1-1 call from Haleyville City Hall, to Congressman Tom Bevill, at the city's police station. Bevill was accompanied by Gallagher and Alabama Public Service Commission director Eugene "Bull" Connor. The phone used to answer the first 9-1-1 call, a bright red model, is now in a museum in Haleyville, while a duplicate phone is still in use at the police station.
AT&T made its first implementation in Huntington, Indiana, the hometown of J. Edward Roush, who sponsored the federal legislation to establish the nationwide system, on March 1, 1968. However, the spread of 9-1-1 implementation took many years. For example, although the City of Chicago, Illinois, had access to 9-1-1 service as early as 1976, the Illinois Commerce Commission did not authorize telephone service provider Illinois Bell to offer 9-1-1 to the Chicago suburbs until 1981. Implementation was not immediate even then; by 1984, only eight Chicago suburbs in Cook County had 9-1-1 service. As late as 1989, at least 28 Chicago suburbs still lacked 9-1-1 service; some of those towns had previously elected to decline 9-1-1 service due to costs and—according to emergency response personnel—failure to recognize the benefits of the 9-1-1 system. By 1979, 26% of the U.S. population could dial the number. This increased to 50% by 1987 and 93% by 2000. As of December 2017 , 98.9% of the U.S. population has access.
Conversion to 9-1-1 in Canada began in 1972, and as of 2018 virtually all areas, except for some rural areas, such as the Northwest Territories and Nunavut, are using 9-1-1. As of 2008 , each year Canadians make twelve million calls to 9-1-1.
On September 15, 2010, AT&T announced that the State of Tennessee had approved a service to support a text to 9-1-1 trial statewide, where AT&T would be able to allow its users to send text messages to 9-1-1 PSAPs.
Most British Overseas Territories in the Caribbean use the North American Numbering Plan; Anguilla, Bermuda, the British Virgin Islands, and the Cayman Islands use 9-1-1.
On October 3, 2016, sixteen states of Mexico switched their emergency phone number from 0-6-6 to 9-1-1, and the whole country converted in June 2017.