Samoa changed its official time zone in 2011 so its New Year's Eve would align more closely with Australia and New Zealand.
On December 29, 2011, Samoa moved westward across the International Date Line by skipping December 30. The country went from being one of the last places to begin a calendar day to being one of the first. As a result, the first New Year's Eve after the change arrived on December 31, 2011, after Samoa had no December 30 that year.
The government cited Samoa's economic relationships with Australia and New Zealand, which had become important trading and business partners. The old calendar position left Samoa nearly a full working day behind those countries, while the new position placed it on the same side of the date line.
American Samoa, a separate U.S. territory, did not make the same switch and remained on the opposite side of the date line. This is why nearby Samoan communities can celebrate New Year's Eve on different calendar days.