I was looking in Upper Michigan and INIDANA and I cannot see any evidence of TIME ZONES being defined. Are they defined?
If they need to be added, I am not that good at ADMINISTRATIVE BOUNDARIES to feel confortable to add them.
Greg
Time zones are in the category of type of information not put into the OSM database. The thinking is that because they cannot be verified independently, such as with a GPS or imagery, that they are not a good fit. Applications or map drawings who need to show or use time zones should get time zone boundaries separately and mix it with OSM data at time of use.
Note that administrative boundaries would not qualify today to be added to the OSM database for the same reason, but they were added earlier before that guideline was used.
There is plenty information in the OSM database that is incorrect. Timezones are usually at the boarder of TOWNSHIPS or COUNTIES. I do not see why we cannot add this information. If you do not think it is accurate, do not use it.
Currently only Russia has timezones: http://taginfo.openstreetmap.org/tags/?key=boundary&value=timezone
See overpass turbo link!
The key timezone is more used, but mostly to define which timezone is used for an object and not to define timezones.
Time zones are in fact defined and mapped in OSM:
Central time zone for example.
Here’s what it looks like in the inspector:
Some have argued that they don’t belong in OSM, but they are presently mapped.
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Here’s a more recent discussion about time zone boundaries and time “zone” “boundaries”, for those who are morbidly curious:
Getting rid of those time zone boundary relations that duplicate administrative boundaries is very high on my list, I plan to deal with them as soon as the abandoned railways are done 
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Please do! They make editing along those boundaries a challenge. I do think they transcend what is marginally observable on the planet. Plus in web mercator it all starts to get very dubious above 85 degrees, where they all come together.
But not before you get rid of abandoned railways…
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The relations that extend above 85 degrees don’t duplicate administrative boundaries. Those pole-to-pole relations are the ones I really look askance at, because each one is just a collection of marginally related features, unioned together as a single geometry.
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