Guy Harris wrote:
what particular administrative region of Kentucky would be the biggest one that should be tagged with timezone=America/Kentucky/Louisville? Or *is* there no such region?
Sorry, I don't know. That would require research. The Shanks data could be examined to find a set of locations whose time zone histories equal that of Louisville since 1970, as far as Shanks is concerned. But that would take a lot of work, I'm afraid. Hundreds, probably thousands of locations would have to be examined, by hand. Or someone would have to scan the data and try to automate the search. Either way, the results would not be that reliable. More reliable would be to consult newspapers of all the locations that plausibly have had the same time zone history as Louisville since 1970, and check for time zone announcements in these newspapers. If you change the time horizon to 1950 instead of 1970, you'll have more work to do, not only because there are more newspapers to read and more of them are not digitized, but also because there is more local variance in the rules the further you go back. I hope it's understood I'm not volunteering to do all this.