Time Zoning

"John lives in an East Coast state and Mary in a West Coast state. During a phone conversation one night, they realize that it is the same time in both locations. How can this be?" I'm pleased to say my knowledge of US time zones was good enough to figure this out. Here's a clue: in the sparsely populated west, time zones sometimes don't follow state boundaries, but conform instead to the closest economic center. For example, northern Idaho is on Pacific time rather than Mountain time like the rest of the state, because Spokane, Washington is the dominant economic center. That won't give you the answer, but it's an important clue. Puzzle from Futility Closet, answer here. BTW, anyone who would call at this time should be punished severely.