You'll want to be careful about calling your friends and family in California - the time is now an hour earlier in that western state, due to Daylight Savings Time (DST) taking effect at 2 AM this morning. However, a call to Chicago is easier to calculate, since there is now only an hour's difference in time.
A few states and territories - including Arizona - do not change their clocks back and forth each year, instead electing to hold tight through the seasons. Other locations that do not change with DST include Hawaii, Puerto Rico, the US Virgin Islands and the American Samoa. But, just to make it a little more confusing, certain Indian Reservations, even some in Arizona such as the Navajo Nation, DO follow DST.
So, if all this is making your head spin, and you're not quite sure what time it is anywhere any more, well, here's a hint. Go to Google, and type into the search box, "What time is it in California" or Chicago, or New York or even Britain, for that matter. Google will happily show you a little clock and give you the current time in whatever location you ask about.
In the meantime, you can be satisfied knowing that Arizona is steadfast, and doesn't flit back and forth with the clock!