The island nations of Kiribati and Samoa are the first countries to celebrate the new year. This is due to their position immediately west of the International Date Line, which determines the start and end of the time zone cycle. Hawaii is among the last to celebrate the new year.
The International Date Line, located at 180 degrees longitude and on the exact opposite side of the earth of the prime meridian, denotes the passage of a calendar date from the day before. The countries west of the line move into a new day first, and other countries (moving westward) follow.