At the end of 1994, part of Kiribati had no 31 December. The 30th was followed straight by 1 January. The day was not celebrated, not moved, not made up for later. For the people there it simply did not happen.
Behind it was no calendar joke but an administrative problem that had grown over decades. Kiribati stretches across several thousand kilometres of Pacific, from the Gilbert Islands in the west to the Line Islands in the east. The international date line ran straight through it. The west of the country lived in one date, the east in another, permanently 24 hours apart.
Four shared working days
For a government that is more than a curiosity. When one half of the country counts Monday while the other is still on Sunday, the working weeks only partly overlap. Arithmetically, four days a week were left on which offices on both sides were open at the same time. On the others, one part of the state could not be reached from the other. Anyone working in the administration on Tarawa who needed information from the Line Islands waited until the calendars met again.
A country in which one half was permanently a day ahead of the other.
— TerraTally · History desk
The solution was simple and radical. Kiribati moved the date line east so that the whole national territory lay on the same side of it. For the eastern islands that meant a jump of a full calendar day: the Line Islands went from UTC−10 to UTC+14. No territory was ceded and no border drawn, a date was reassigned. That is possible because a time zone is a decision, not a measurement.
before 1995
The date line runs through the middle of Kiribati. West and east are permanently a day apart, with four working days usable by both.
end of 1994
The eastern islands jump forward one calendar day. There, 31 December does not happen.
1995
The whole territory lies east of the line, the Line Islands on UTC+14. The new day begins there first.
A side effect then made the country known. At UTC+14, Kiribati sits further east in timekeeping than any other inhabited place. Since 1995 the new day starts there first, and with it the new year. Around the turn of the millennium the government marketed exactly that, and the trouble of a split calendar turned into a selling point.
What remains remarkable is the act itself. The date line exists nowhere physically. It follows no law of nature and no treaty binding on everyone. It is the result of which time zone each state gives itself, and it shifts wherever a government decides it should.
Kiribati demonstrated that. A country took a day out of its calendar in order to be simultaneous with itself again. On world maps it left a visible kink in the course of the line, and that kink is still there. It is the trace of an administrative decision that cost the people in the east of the country one New Year's Eve.