I’m interested to know about this, too. WaPo... part of the Fake News Media since day one.
About forty years ago I was amazed when my wife told me about the City of Torrance, California having the 911 system when she was a child in the 1950’s. I was raised in Long Beach. Not that far from Torrance, but never heard of 911 until much later. Apparently it was established nationwide in 1968.
Apparently 911 was around in various forms prior to it becoming a national familiarity.