Kiribati was the first country to enter the year 2000 at midnight, according to its time zone.
The Pacific island nation moved the International Date Line eastward around its territory in 1995. This change placed the Line Islands, including Kiritimati, on the side of the line that experiences a new calendar date earlier than many other locations. As a result, Kiritimati became widely identified as one of the first inhabited places to welcome the year 2000.
The phrase “first country” needs context. Different islands and time zones can make headlines seem contradictory, and the exact first inhabited location depends on which territory and time standard are being compared. Kiribati's unusual geography is the key fact behind its prominent millennium celebrations.
The change was designed to keep Kiribati's scattered islands on the same calendar date for practical and administrative reasons. It was not caused by the Earth rotating faster or by a special millennium rule; it resulted from an official time-zone and date-line decision.