The zone naming is not consistent. Of course, some reasoning lies behind it, but just looking at the names: they are not of database quality. That's a hurdle to a non-TZ developer. America/Boise refers to a county and a city in the USA. America/Edmonton refers to a city not in the USA but in Canada. America/Sao_Paulo refers to a city in Brazil. America/Costa_Rica refers to a country. If this works for you, then it works. Don't change it! And don't discuss it either! In reply to: Paul Eggert:
single zone name (e.g. Georgia) being a valid zone name (instead of Asia/Tbilisi). That's another bad example. The vast majority of uses of the name "Georgia" in English refer to the USA state, not to the nation of Georgia. For USA residents a USA-centric approach is obvious, for others probably a more global, it est country-like, approach serves logic better. But, if it works for you... &c.
Here's a sample 'tzselect' interaction to show how this might work for your example user in Boise. $ tzselect Please identify a location so that time zone rules can be set correctly. Please select a continent or ocean. ... Please select a country. ... Please select one of the following time zone regions. Ah, that is nice! I want to know what time it is in Boise Idaho, but I first have to tell you what (general) time it is over there. I don't know, that's why I asked you.....