Time zones - Where do they start / change ?

Question

I've often confused by timezones and where they start. E.g. Is there a particular point in countries where one side of the road is 4pm and one is 5pm?

Answer 1

The timezones start at the Greenwich Meridian that runs through England. They are theoretically 15 degrees of longitude, however they have been altered to suit real-life administrative needs so the lines aren't perfectly straight.  For ex. China should be in several timezones, but is only in one. Typically the modified boundaries fall in relatively unpopulated areas or where there is a natural boundary of some kind. For ex. in the California/Nevada/Arizona tri-state area the Colorado River marks the boundary so if you cross the river you've changed time zones. However, in this instance that doesn't mean you've changed times.  For 1/2 the year Arizona and California are the same time even though they are in different timezones sine Arizona does not recognize Daylight Savings Time.

Answer 2

The time zones start in London, England, at the Greenwichhmeridianm, it's the reference point for taking the world time of any country around the world; however where is located the changing place of the date is on themeridianm 180ª. Near this meridian is located Tonga Island,Tahitií, and Western Samoa. In that point  goes the international dating line. For instance, if in Western Samoa is 3:00 PM of today august 19, in Tonga Island is 3:00 PM of tomorrow august 20.

Answer 3

Time zone lines usually follow state and/or country borders. If you know whats state you in you shold know that time zone your in. most cell phones automatically adjust their time to your time zone.