Allison Schrager, a New York-based economist and writer, explains here how the US could coordinate on just two time zones:
This year, Americans on Eastern Standard Time should set their clocks back one hour (like normal), Americans on Central and Rocky Mountain time do nothing, and Americans on Pacific time should set their clocks forward one hour. After that we won’t change our clocks again – no more daylight saving. This will result in just two time zones for the continental United States. The east and west coasts will only be one hour apart. Anyone who lives on one coast and does business with the other can imagine the uncountable benefits of living in a two-time-zone nation (excluding Alaska and Hawaii).
What do you think of Ms Schrager’s proposal? Does the continental US really need four time zones?
Hat tip: Tyler Cowen of Marginal Revolution
prior probability 
For that matter, why not just put everyone in the world on GMT and call it a day? (No apologies for the pun.)
To this I would say, remember every time we “spring forward” or “fall back”, adjusting our clocks to accommodate daylight savings time in this country. I’d challenge you to find one person who this process did not interfere with. Everyone always gets annoyed with the adjustment, and complains that it is either too bright or too dark at a time when they aren’t used to. Imagine the frustration of having a country with only two time zones… Undoubtedly we would have many areas where the lighting is vastly different, yet the time is the same. Some areas may still be dark when children are walking to school, posing a hazard, while other areas may be brightly lit, within the same time zone. For those of you that can’t continue to sleep past the sunrise, expect problems when you’re seeing the sun at an inconvenient time for you. Sure, businesses could benefit greatly from having only 2 time zones, and this could streamline many parts of our life. However, this kind of change would be far reaching in its effects, that may not be so desirable.
MS, to follow-up on your school children example, why not change class to 9am instead of changing the clocks (after all, not everyone has school-age children, etc. etc.)
PC, love the (intended) pun