Matt Johnson <mj1856@hotmail.com> writes:
I did see from the comments in the northamerica file that cover two counties in the Michiana area – LaPorte and Starke. LaPorte county is considered by tzdb to be in Western Indiana and covered by America/Chicago, and the Starke county has its own unique history in America/Indiana/Knox. Since both of those are in the Michiana area, is it possible that America/Indiana/Knox is actually applicable in the other counties of Michiana?
It's possible. It's also possible that there are some areas near the Michigan border which observed DST in the _Eastern_ time zone, undocumented by the tz database, which would also account for an hour difference. Do you know if this was during the summer or winter? These would probably be in America/New_York or America/Detroit. It's unlikely that Starke county's _specific_ history applies to St. Joseph county, since that history includes a USDOT petition that was granted in 1991, whereas St. Joseph county was never (well, not since 1967) on Central time. But pre-2006 EDT usage isn't as well-documented, since it was never strictly legal.