On 3/8/07, Hal Duston [email protected] wrote:
So, I read the US rules as setting the national standard, and then the more regional rules to set the individual timezones before they to were conformed universally to a national standard.
There has apparently been only one time when DST rules were in effect, but not applied uniformly throughout all areas that do practice DST, which was when Hawaii went to DST for three weeks in 1933. The DST rules for NYC, Chicago, Denver, and CA vary only in those historical periods that the US ruleset is silent.
Prior to 1967, in peacetime DST was a local option. A state or subdivision thereof might have changed DST participation while the ones adjacent did not. I can confidently state that there has NEVER been a 'regional rule' that applied to the entire Central Time Zone but not to any other.
I stand by the statement that there should be a single US rule, 6 timezone definitions that use it (EST5EDT, CST6CDT, MST7MDT, PST8PDT, AKST9AKDT, HAST10HADT), and 4 that don't practice DST at present (AST4,MST7,HAST10 [aka HST10], ASST11), and the microzones that represent areas that have changed zones or DST use since 1970, such as the counties in IN that have moved between ET and CT, and toggled their DST use.