Nitpicking a bit, but I'd usually argue that the TZ doesn't change: You went from "America/Chicago" to "America/Chicago". The timezone encapsulates more than ju

Nitpicking a bit, but I'd usually argue that the TZ doesn't change: You went from "America/Chicago" to "America/Chicago". The timezone encapsulates more than just the offset: it also includes when and how DST works. Merely, you went from "1:59:59 am America/Chicago DST=true" to "1:00:00 am America/Chicago DST=false". I'd say this is just terminology, since "CDT" and "CST" work just as well (and how I envision it in my head, mostly due to the official TZ name being "America/Chicago").