zoneinfo, the Unix time zone database, is good software. It converts absolute time to local time subject to local conventions, historical circumstance, and stupid laws. It has to work from at least 1970, so time-loving geeks have filled it with minute local detail about the inconstancy of local timekeeping.
# Part of Kentucky left its clocks alone in 1974.
# This also includes Clark, Floyd, and
# Harrison counties in Indiana.
-5:43:02 - LMT 1883 Nov 18 12:16:58
-5:00 US E%sT 1974 Jan 6 2:00
-6:00 1:00 CDT 1974 Oct 27 2:00
The 2006b update contains the news that Indiana has now standardized their adoption of DST. It also has the fact that this year, Melbourne is delaying the adoption of DST one week to accomodate the Commonwealth Games. But that's all practical stuff; what's fun about zoneinfo is all the learned and detailed comments about local time jurisdictions. Paul Eggert is particularly eloquent.
Shanks writes that Michigan started using standard time on 1885-09-18, but Howse writes (pp 124-125, referring to Popular Astronomy, 1901-01) that Detroit kept