Does Alaska cross into the Eastern Hemisphere?
The Aleutian Islands run so far west from mainland Alaska that the chain crosses the 180th meridian — the line that splits the globe into east and west — and keeps going.
Alaska is the westernmost, easternmost, and northernmost US state. Amatignak Island (179°08′55″W) is the westernmost point in the US by longitude. Keep going west along the same island chain and, instead of running out of islands, you cross 180° and start counting east again — landing on Semisopochnoi Island (179°46′23″E), the easternmost point in the US by longitude.
Superlatives like “easternmost” depend on where the measuring system starts and ends. At the edge of a scale, close neighbors can end up looking like opposites.
What “farthest” or “first” depends on where someone decided to start counting?
Why the antimeridian works this way
Longitude is measured east or west from the Prime Meridian (0°) at Greenwich, up to 180° in each direction — so 180°E and 180°W are the same line, halfway around the globe from Greenwich. Everything just east of it reads as a very large positive "east" number; everything just west of it reads as a very large positive "west" number. Two points a few dozen miles apart, straddling that line, end up as far apart as two longitude readings can possibly be — one near the top of the "east" scale, one near the top of the "west" scale — even though neither number reflects how close together the islands actually sit.
The map above shows only the far-western tip of the Aleutian chain, reprojected so the 180th-meridian seam doesn't split the islands visually; mainland Alaska continues roughly 1,200 miles further east, off the map. Island outlines are simplified Natural Earth data, not survey-grade boundaries.
Both islands are uninhabited specks in the Aleutians, roughly 25 miles (40 km) apart on the same island chain — yet by the numbers, one is the most western point in the country and the other is the most eastern. The 180th meridian does the same thing to time that it does to direction: cross it a little farther north, between the two Diomede Islands, and instead of "east" flipping to "west" it's today flipping to tomorrow — the same islands are 2.4 miles apart and end up on opposite sides of the international date line. Wherever the antimeridian runs, it turns a small, arbitrary line-drawing choice into an outsized effect on the numbers next to it.
Related exhibits
Sources: Semisopochnoi Island 51°57′42″N 179°46′23″E; Amatignak Island 51°16′07″N 179°08′55″W (published US geographic extreme points, per Wikipedia and WorldAtlas). Island shapes: Natural Earth 10m. The map shows only the far-western Aleutians; mainland Alaska continues roughly 1,200 miles further east, off the map.