International Date Line Map

How it works

No treaty defines the International Date Line. Each country chooses its own date, and the line is simply drawn between neighbours who chose differently. This page draws the conventional line from the well-known description as a set of hand-placed corners: down 180° from the pole, east through the Bering Strait between the Diomede Islands, west of St Lawrence Island, west around the Aleutians, down 180° to 5° N, east around Kiribati's Line Islands to 150° W, back west between the Cook Islands and Tokelau, between Samoa and American Samoa, east of Tonga and the Kermadec and Chatham Islands, then 180° to Antarctica. Each corner was placed so the islands nearby fall on the side of the date they really keep. Other atlases draw the corners a little differently.

Howland and Baker Islands, two uninhabited US atolls, keep UTC-12 but sit inside the drawn Kiribati bulge; the conventional line ignores them and so does this map, with a note. The nearest point is found against the drawn line and is a great-circle distance. Country outlines are Natural Earth data served from this site; small island states not in that file are shown as markers only.

Questions

Why does the International Date Line zigzag?

Because it is drawn around countries, not through them. Russia's Chukotka and Alaska face each other across the Bering Strait, so the line bends east there; the western Aleutians lie beyond 180° but are American, so it bends west; Kiribati moved its eastern islands to the western date in 1995; Samoa and Tokelau switched sides in 2011; Tonga and New Zealand's outlying islands keep the western date. Each kink is a decision about which neighbours to share a working week with.

What happens when you cross the International Date Line?

Going west, from Alaska toward Russia or from Hawaii toward Japan, the calendar jumps forward a day. Going east, the same day repeats. Ships and aircraft simply change the date in the log; nothing physical marks the line at sea.

Where is it tomorrow first?

Kiribati's Line Islands, including Kiritimati, at UTC+14: they start each date before anywhere else. Tonga, Samoa and Tokelau (UTC+13) follow. The last places to finish a date are Howland and Baker Islands at UTC-12, uninhabited, and then American Samoa and Niue at UTC-11.

Does the Date Line run exactly along 180° longitude?

Only in the open ocean. It leaves 180° north of Wrangel Island, in the Bering Sea, around the Aleutians, and for a long stretch of the South Pacific from Kiribati to south of the Chatham Islands, where it lies as far east as 150° W.