Blizzard has recently released a new patch for WoW that puts all of the WoW servers in one screen instead of being distributed over all the varying time zones.
New Patch - Realm-Selection Screen Changes
We released a small patch today that removed the time zone tabs (Pacific, Mountain, Central, Eastern) in order to streamline the realm-selection process for players. Additional changes to further streamline the realm-selection process will be implemented in the future.
The patch will be automatically downloaded and installed the next time you exit World of Warcraft completely and then restart the game. Prior to installing the patch, some players may see issues with the realm-selection screen. Installing the patch will resolve these issues.