I have documentation for Wisconsin's variation of CDT. http://www.legis.state.wi.us/statutes/Stat0175.pdf; 175.09, enacted in 1923, sets Wisconsin time to "central time" and provides penalties for businesses not following the "standard of time." In 1957 Wisconsin deviated from the rest of the central zone by enacting statute 175.095. This statute directs that Central Daylight Time will being at 1 A.M. on the last Sunday of April. Updated versions of this statute only changed the day of change and kept the time of change at 1 A.M. < http://www.legis.state.wi.us/statutes/Stat0175.pdf > Before the addition of statute 175.095 it was assumed that statute 175.09 did not override Central Daylight Time (Opinions of the Attorney General of the State of Wisconsin - 1942), with his opinion that "[...] that the words 'commonly known as central time' are more than merely descriptive and that they in fact constitute the definition of standard time in the state of Wisconsin." Adding, "I may say in concluding this opinion that there seems to be some misunderstanding as to the purpose of the Wisconsin law relating to standard time. It has been referred to in many instances as an anti-daylight-saving statute. Such a statement is, in my opinion, inaccurate." It should be assumed that Wisconsin followed the America/Chicago rules before 1957, when the 175.095 statute was passed into law. During the years of 1974 and 1975 this statute appears to have been ignored entirely in favor of the Federal law, as it would have advanced time additionally one extra hour. (Opinions of the Attorney General of the State of Wisconsin - 1974) In 1987 this statute (175.095) was updated to reflect the date change, however the time 1 A.M. was left in place. Operationally this statute is currently enforced at the 1 A.M. time of change. Because the local "bar time" in the state corresponds to 2 A.M., a number of citations are issued for the "sale of class 'B' alcohol after prohibited hours" within the deviated hour of this change every year (0100-to-0200 America/Chicago, 0200-0300 America/Wisconsin). Should anyone require additional comments, please contact Larry M. Smith <SgtChains-TZ@FahQ2.com> Rule Wisconsin 1957 1973 - Apr lastSun 1:00 1:00 D Rule Wisconsin 1957 max - Oct lastSun 2:00 0 S Rule Wisconsin 1976 1986 - Apr lastSun 1:00 1:00 D Rule Wisconsin 1987 max - Apr Sun>=1 1:00 1:00 D # Zone NAME GMTOFF RULES FORMAT [UNTIL] Zone America/Wisconsin -5:50:36 - LMT 1883 Nov 18 12:09:24 -6:00 US C%sT 1920 -6:00 Chicago C%sT 1936 Mar 1 2:00 -5:00 - EST 1936 Nov 15 2:00 -6:00 Chicago C%sT 1942 -6:00 US C%sT 1946 -6:00 Chicago C%sT 1956 -6:00 Wisconsin C%sT 1973 -6:00 US C%sT 1975 -6:00 Wisconsin C%sT