History
Why Samoa skipped a whole day in 2011
Samoa moved across the International Date Line at the end of 29 December 2011, so Friday 30 December never occurred there. It is a vivid demonstration that civil dates are a policy choice.
A legal change, not time travel
Samoa’s International Date Line Act 2011 changed the country’s standard time from the American side of the date line to a time 13 hours ahead of UTC. The change took effect at midnight following Thursday 29 December 2011.
Friday 30 December was omitted
The next local calendar date was Saturday 31 December. The clock did not make Earth rotate differently; Samoa changed the civil date attached to the same sequence of instants. Historical records and date-based systems must therefore recognise that the local date was skipped.
Why the line bends
The US Naval Observatory notes that Samoa’s move was made by a government for local interests. It shows why the International Date Line is a convention that follows jurisdictions and practical relationships, not a rigid line imposed by geography.