[scrabblehack]

I’ve thought Newfoundland should be on the hour:
52.5 - 67.5: Atlantic
67.5 - 82.5: Eastern
82.5 - 97.5: Central
97.5 - 112.5: Mountain
112.5 - 127.5: Pacific

The Michigan mitten and Tennessee would shift to Central time...

[sopo]

Amazing the lack of consensus here, or maybe not, considering stepping one foot to the west on any of those boundaries changes you ST to DST