Apparently, unknown to all of us, the Yukon Territory did so six years ago.
No disrespect intended to the good people there, but the Yukon Territory really isn't on Americans' radar, unless it would be Alaskans.
I have to imagine, with being so far north, and the extremes of daylight and dark you have there at various times of the year, being on either standard time or DST wouldn't make that much of a difference in people's lives.