I know in the Pacific Northwest
They did away with alot of the old #5,#1 Cross bar equipment as well as the Step-by Step,, Pannel-sxs switches in the mid to late 80's(imagine that some of that stuff was 50+years old in some cases, and still worked) At my house it was Nov of 1981 as I recall. The last place that switched to the new equipment was Portland Cypris which still had the old Step by step centeral office and the Portland Harold St which had a #5 cross bar, which for many years was a standard in alot of places in this part of the country, including where I grew up in Vancouver, Wa. In 1986, the PUC told the phone co's that they were required to(go to electronic switching), in order for everyone to have equal access, meaning that they could choose a different long distance carrier than AT&T. I know in our neighborhood, which is Portland Belmont(503- 230 to 239 etc) we have ESS 1-A equiped central office, a relic by todays standards.AS a result of that, I can still use my rotarty phones that will never die.