Paul's right. I've come to the conclusion that it is better to view any data pre-1970 as a suggestion provided to the end user with warnings. Expanding the data to include more questionable data just leads to a false sense of security.

On Sun, Dec 6, 2015 at 4:49 PM, Paul Eggert <eggert@cs.ucla.edu> wrote:

Clifford Ribaudo wrote:

I would like to propose that Zone Names be added for each state and which at a minimum simply model the adoption of DST in 1966.

As you know, the U.S. was a huge zoo of local time zone jurisdictions before 1970, and the same is true elsewhere in the world. The tzdata project considers most of this data to be out of scope, as we simply don't have the resources to maintain the large, unreliable database that would be needed to cover the world before 1970.

That being said, there is a spot for out-of-scope data if you can find good sources for it. It's the file 'backzone', and it contains entries such as Europe/Guernsey that can be helpful for apps like yours, along with some other entries that are dicier. If you can come up with well-sourced data for North Carolina and propose a patch for 'backzone', we could slide it in there. For info about doing that, please see:

https://github.com/eggert/tz/blob/master/CONTRIBUTING

https://github.com/eggert/tz/blob/master/Theory