[tz] tz dependency lat & lng

[random832 at fastmail.us]

On Thu, Sep 5, 2013, at 21:50, Gwillim Law wrote:
> My data are incomplete, but the time zone boundary in Kentucky has
> followed
> county lines since 1961, as far as I can tell. Before 1961 there were
> definitely some Kentucky counties that were divided between Eastern and
> Central. I've listed the results of my investigations at
> http://www.statoids.com/tus.html. Recent changes can usually be found
> described in dockets of the Department of Transportation.

The problem is that Louisville is one of those small areas that didn't
consistently use DST in the 1970s, and it's unclear what locations
around them followed their example.