I have a mapping app in which I need to display the borders between U.S. time zones. The easiest and most accurate way would be to feed in a list of lat/long coordinates representing the vertices of these borders, and "connect the dots".
So, the question, simply put, is whether a publicly-available, free database of these geocodes exists, and where?
A shapefile of the TZ timezones of the United States
Last data update: September 30, 2012
The tz_us shapefile captures the boundaries of the TZ timezones of the United States, as of TZ 2012c.
The geometries are entirely derived from the countyp020p and timeznp020 shapefiles provided by the National Atlas.
All the TZ timezones of United States listed in TZ’s zone.tab are represented, except for America/Shiprock which is included in America/Denver.
Shapefile Zipped (Direct Link) http://efele.net/maps/tz/us/tz_us.zip
I haven't looked at the data, but check out this USGS version. There's some other information on this page. I have a feeling that the data isn't reflecting some of the local changes like Arizona not switching to daylight savings time.
This is likely too late for your needs, but http://OnTimeZone.com has what you are looking for. It is more current, more detailed, and more accurate than the efele.net data. It also has data about local deviations from official time zone observance.
The data is available for download in multiple formats and is free for non-commercial, non-governmental use.
There is a new source of timezone maps as shapefile or geojson at https://github.com/evansiroky/timezone-boundary-builder. The data from that project is sourced from Open Street Map.
