The data itself could be based on creative choices. For example: deciding the timezones for disputed territories, handling ambiguous historical date changes, the divisions of territories into timezones etc.
These are creative decisions, I worked at a largish tech company which developed it's own timezone database and it's a non-trivial process to decide how to divide geographic locations into timezones. A lot of locations you have to pre-emptively allocate a timezone, not because they have a different timezone from their surrounding area, but because they might at some point in the future have one.
The American Atlas (the work under debate) divides Indiana into 345 different areas and gives a timezone history for each one, but there are literally millions of ways you could have subdivided Indiana and ended up with different areas, it comes down to arbitrary decisions on how you group together different timezone changes. The 345 different areas were presumably chosen based upon a creative process.
"The American Atlas (the work under debate) divides Indiana into 345 different areas"
And the timezone file in question does not, unless I am very much mistaken. So even if we stipulate your point, which I don't, it wouldn't apply because the timezone isn't a copy of that aspect, and again, you can't copyright facts. Even if the timezone file used the same divisions, what would be protected is the Atlas' textual description of them, their textual history, whatever cute anecdotes are written up, not the fact of existence of 345 different areas in Indiana which have at some point had some sort of time zone difference.
You can take whatever facts in the world you like from whatever source, write them up in your own words, and the original author of the facts has zero copyright claim on your words. Copyright protects expressions, not facts. If you're managed to stretch your definition of copyright to the point that it says you can actually own facts, you have, by definition, in fact exceeded the domain of copyright. Nobody owns those 345 different areas of Indiana, only the words creatively used to describe them.
I think you miss the point, the division of areas for time-zoning purposes can be done in millions of different ways. The selection of a particular way to do it is a creative choice.
This inevitably means that the copyright in a factual compilation is thin. Notwithstanding a valid copyright, a subsequent compiler remains free to use the facts contained in another's publication to aid in preparing a competing work, so long as the competing work does not feature the same selection and arrangement. As one commentator explains it: "[N]o matter how much original authorship the work displays, the facts and ideas it exposes are free for the taking. . . . [T]he very same facts and ideas may be divorced from the context imposed by the author, and restated or reshuffled by second comers, even if the author was the first to discover the facts or to propose the ideas." Ginsburg 1868.
AFAIK, the tz data just maps timezones and date ranges to offsets. Your different areas don't matter at all here, because the tz data doesn't care about the mapping of geographical regions to time zones.
I'm not sure I follow, the tzdata AFAIK is primarily geographic mappings to time offsets and transitions ? - the number of timezones which are identified by timezone name like UTC are relatively few.
tzdata says absolutely nothing about geography. "America/New_York" is just a name for a certain set of historical timezone data, but it's completely up to users to decide what geographical area they want to associate with it.
These are creative decisions, I worked at a largish tech company which developed it's own timezone database and it's a non-trivial process to decide how to divide geographic locations into timezones. A lot of locations you have to pre-emptively allocate a timezone, not because they have a different timezone from their surrounding area, but because they might at some point in the future have one.
The American Atlas (the work under debate) divides Indiana into 345 different areas and gives a timezone history for each one, but there are literally millions of ways you could have subdivided Indiana and ended up with different areas, it comes down to arbitrary decisions on how you group together different timezone changes. The 345 different areas were presumably chosen based upon a creative process.