The International Date Line is the strangest line on this list, because it doesn't exist in any legal sense. No treaty, no governing body, no agreed coordinates. It's the join where neighbouring countries' time zones stop being a day apart, and any country can move it by changing its own clocks. Several have.
That's why the map below draws it dashed. The solid line is the 180th meridian, which is a real coordinate, and the two are worth comparing side by side. Three countries have territory on the 180th meridian: Russia, Fiji and Antarctica. The date line bends around all three.
The table is computed against the 180th meridian for that reason. You can't compute against the date line itself when the line is drawn precisely to avoid having anything to intersect.
Worked out by intersecting the line with national borders, so the order is the order you’d meet them tracing the line north to south. Tap any row to fly the map to that crossing.
| # | Country | Enters and leaves | Distance |
|---|---|---|---|
| 1 | 520 km | ||
| 2 | 50 km | ||
| — | not a country | 590 km |
The table is computed against the 180th meridian, not the date line. The date line has no official coordinates to compute against, which is the point the table is making.
Coming down from the North Pole the line follows 180° until roughly 75°N, then swings east to keep Wrangel Island and the Chukotka peninsula on the Russian side. It threads the Bering Strait at about 169°W, between Big Diomede, which is Russian, and Little Diomede, which is American. Locals call them Tomorrow Island and Yesterday Isle.
South of there it bends west past St Lawrence Island, then crosses into the eastern hemisphere around 170°E to pass between Russia's Commander Islands and the western tip of the Aleutians. Back to 180° at about 48°N, then a long run south through empty Pacific.
The big bend is Kiribati's. In 1995 the country moved the line roughly 2,000 km east to around 150°W so all three of its island groups would share a date, having previously run its administration across a border that split the working week. That put the Line Islands on UTC+14, the furthest-forward time zone in the world.
Further south it runs between Samoa and American Samoa, 125 km apart and a full day out of step. Samoa and Tokelau jumped sides at the end of 2011, skipping 30 December entirely, to line up with Australia and New Zealand for trade.
Three entries come back: Russia, Fiji and Antarctica. Each one explains a bend.
Russia's Chukotka crosses 180° between roughly 65°N and 71.5°N. If the date line followed the meridian, the far eastern tip of Russia would be a day behind the rest of Chukotka, so the line jogs east and the whole region stays on UTC+12.
Fiji is the clearest case. Vanua Levu and Taveuni straddle 180° directly, and Taveuni has a signposted marker on the meridian that was for years advertised as the date line. Fiji keeps the whole archipelago on UTC+12, so the line runs east of the country.
Antarctica is the exception the convention fudges. The 180th meridian crosses it from the coast at about 84.7°S to the South Pole, and the date line is drawn straight down the meridian there because there's nothing to avoid. Antarctic stations pick whichever time zone suits their supply chain; Amundsen-Scott at the pole runs on New Zealand time.
Going west across the line you lose a day: Tuesday becomes Wednesday. Going east you gain one and live the same date twice. Flights between Auckland and Los Angeles do this routinely, which is why a 12-hour flight can land before it took off by the calendar.
The world's time zones span 26 hours rather than 24, because of the UTC+14 and UTC−12 extremes either side of the Pacific bends. For roughly two hours out of every 24, three different calendar dates are in use somewhere on Earth at once.
The first inhabited place to see a new year is Kiritimati in Kiribati at UTC+14. The last are Baker and Howland Islands, uninhabited US territories at UTC−12. American Samoa is the last inhabited one, at UTC−11.
The 180th meridian is intersected with the Natural Earth 1:110 million borders. Because the dataset cuts every feature at the antimeridian, the intersection runs at 179.99°E and 179.99°W and the two results are merged. Otherwise the line lands on the seam and returns nothing.
The date line drawn on the map is the conventional course used by almost every published map, and it's approximate on purpose, since there are no official coordinates to be precise about. The vertices follow the standard description: east around Chukotka, through the Bering Strait, west past the Aleutians, then the Kiribati bulge and back west between the two Samoas.
Treat the dashed line as a sketch of current practice. Any country either side of it can redraw its own piece next year by act of parliament, and historically they do it about once a decade.