“Alaska and Hawaii have the same issue, There is a Halachic Debate where the International Date line is. According to the secular world, the International date line is approximately 180 Degrees from London. Which is considered the start of Time, However Halacha says Jerusalem is 0 degrees not London, so that moves the International date line”
This is a poor explanation, because it does not reflect the views of most poskim. Not even as a certainty the psak of the one shita that says the date line is 180 degrees from Yerushalyaim.
The article and map referenced by iacisrmma is very informative.