How do I determine what time zone I'm in if I go from one state to another? like, if from NY to california, how do I know what time zone california is in?

A little US time zone history lesson with a world map of time zones can be found here: http://www.infoplease.com/ipa/A0855474.html California is in the Pacific Time Zone. It does observe daylight savings. Arizona is Mountain Time - they do not observe daylight savings change. they are one hour behind California some of the time, when California springs forward Arizona and California have the same time. For the USA lower 48 a time zone map can be found here: http://geography.about.com/library/misc/ntimezones.htm Indiana decided to really muck with time - for information on that read: http://geography.about.com/gi/dynamic/offsite.htm?site=http://www.mccsc.edu/time.html