Why was the number 911 decided for the emergency call in the USA?

Answer 1

The exact reasons are unknown.

However, some points are clear. First, most (but not all) telephone companies in the United States and Canada reserved the N11 codes (N = 2 through 9) for special purposes; for example, 411 was used for directory assistance (directory inquiries) well before 911 was introduced for emergency calls. For that reason, the eight N11 combinations were never used for either area codes or exchange prefixes. Of the eight N11 codes, 911 is the least likely to be accidentally dialed by user error or equipment fault, and yet it is easy to remember and easy to dial.

The 911 emergency number was introduced in some parts of Canada and the U.S. beginning in 1968, but it took many years to spread nationwide.