Daylight saving time in the US
Most of the country moves clocks forward one hour at 2:00 AM on the second Sunday in March and back on the first Sunday in November, under the Energy Policy Act of 2005. Hawaii and most of Arizona stay on standard time all year, as do Puerto Rico, Guam and the US Virgin Islands. The Navajo Nation in Arizona does observe daylight saving time.
Business hours across the zones
When it is 9:00 AM in New York it is 6:00 AM in Los Angeles, so a meeting that suits both coasts usually falls between 12:00 and 5:00 PM Eastern. US stock markets open at 9:30 AM and close at 4:00 PM Eastern time.