The three-digit telephone number "9-1-1" has been designated as the "Universal Emergency Number," for citizens throughout the United States to request emergency assistance. It is intended as a nationwide telephone number and gives the public fast and easy access to a Public Safety Answering Point (PSAP).

In the United States, the first catalyst for a nationwide emergency telephone number was in 1957, when the National Association of Fire Chiefs recommended use of a single number for reporting fires.

In 1967, the President's Commission on Law Enforcement and Administration of Justice recommended that a "single number should be established" nationwide for reporting emergency situations. The use of different telephone numbers for each type of emergency was determined to be contrary to the purpose of a single, universal number. Other Federal Government Agencies and various governmental officials also supported and encouraged the recommendation. As a result of the immense interest in this issue, the President's Commission on Civil Disorders turned to the Federal Communications Commission (FCC) for a solution.

In November 1967, the FCC met with the American Telephone and Telegraph Company (AT&T) to find a means of establishing a universal emergency number that could be implemented quickly. In 1968, AT&T announced that it would establish the digits 9-1-1 (nine-one-one) as the emergency code throughout the United States.

The code 9-1-1 was chosen because it best fit the needs of all parties involved. First, and most important, it meets public requirements because it is brief, easily remembered, and can be dialed quickly. Second, because it is a unique number, never having been authorized as an office code, area code, or service code, it best meets the long range numbering plans and switching configurations of the telephone industry.

Congress backed AT&T's proposal and passed legislation allowing use of only the numbers 9-1-1 when creating a single emergency calling service, thereby making 9-1-1 a standard emergency number nationwide. A Bell System policy was established to absorb the cost of central office modifications and any additions necessary to accommodate the 9-1-1 code as part of the general rate base. The Enhanced 9-1-1, or E9-1-1, subscriber is responsible for paying network trunking costs according to tariffed rates, and for purchasing answering equipment from the vendor of their choice.

On February 16, 1968, Senator Rankin Fite completed the first 9-1-1 call made in the United States in Haleyville, Alabama. The serving telephone company was then Alabama Telephone Company. This Haleyville 9-1-1 system is still in operation today. On February 22, 1968, Nome, Alaska implemented 9-1-1 service.

In March 1973, the White House's Office of Telecommunications issued a national policy statement which recognized the benefits of 9-1-1, encouraged the nationwide adoption of 9-1-1, and provided for the establishment of a Federal Information Center to assist units of government in planning and implementation. The intense interest in the concept of 9-1-1 can be attributed primarily to the recognition of characteristics of modern society, i.e., increased incidences of crimes, accidents, and medical emergencies, inadequacy of existing emergency reporting methods, and the continued growth and mobility of the population.

In the early 1970s, AT&T began the development of sophisticated features for the 9-1-1 with a pilot program in Alameda County, California. The feature was "selective call routing." This pilot program supported the theory behind the Executive Office of Telecommunication's Policy. By the end of 1976, 9-1-1 was serving about 17% of the population of the United States. In 1979, approximately 26% of the population of the United States had 9-1-1 service, and nine states had enacted 9-1-1 legislation. At this time, 9-1-1 service was growing at the rate of 70 new systems per year. By 1987, those figures had grown to indicate that 50% of the US population had access to 9-1-1 emergency service numbers.

In addition, Canada recognized the advantages of a single emergency number and chose to adopt 9-1-1 rather than use a different means of emergency reporting service, thus unifying the concept and giving 9-1-1 international stature.

At the end of the 20th century, nearly 93% of the population of the United States was covered by some type of 9-1-1 service. Ninety-five percent of that coverage was Enhanced 9-1-1. Approximately 96% of the geographic US is covered by some type of 9-1-1. 

Many changes and upgrades have been made since the first 9-1-1 calls were placed and the advent of new technologies such as cell phones and Voice over IP (internet) phones have forced many new changes to the 9-1-1 system.  This system is always being upgraded and improved to provide people with the best possible help in an Emergency situation.