How can Alaska be both the westernmost and easternmost state?

Alaska's Aleutian Island chain stretches across the 180th meridian, the line where western longitude turns into eastern longitude. Land on one side of that line has western longitude and land on the other has eastern longitude, so Alaska contains both the most westerly and the most easterly longitudes of any US state. Which state counts as easternmost depends on the definition used. [1] [2]

Longitude is measured from the prime meridian at Greenwich, England, east or west up to 180 degrees. The 180th meridian is halfway around the world from Greenwich. It passes through the Aleutians, so Alaska's westernmost portion lies in the Eastern Hemisphere, and Britannica notes that Alaska is technically in both hemispheres. [1] [3]

The State of Alaska's geography guide names Amatignak Island, at 179° 06' 31" west, as the land with the most westerly longitude. About 70 miles away, across the meridian, Pochnoi Point on Semisopochnoi Island sits at 179° 46' east, the most easterly longitude. The US Geological Survey lists the distance between these two points as 63 statute miles, which differs from the roughly 70 miles in the state guide, so the exact figure depends on the source and how it is measured. [1] [4]

Under the global longitude definition, Alaska is both easternmost and westernmost. Under the everyday map definition, where left is west and right is east, the answer changes. The state guide says the farthest western point is then Cape Wrangell on Attu Island, about 300 miles farther along the chain, and the farthest eastern point is near Camp Point in southeastern Alaska. [1]

ThoughtCo takes a similar approach. It lists Alaska (Cape Wrangell, 172° 27' east) as the westernmost state, but gives Maine, at West Quoddy Head (66° 57' west), as the easternmost. For the lower 48 states alone, it lists Maine as easternmost and Washington (Cape Alava) as westernmost. USGS measures the distance from West Quoddy Head, Maine, to Cape Wrangell, Alaska, as 4,831 statute miles. [5] [4]

Most flat maps put Alaska on the far left, which reinforces the idea that it can only be west. Maps have to split the round Earth somewhere, and the usual cut is near the 180th meridian. The International Date Line jogs west of 180° to keep the whole state on the same calendar date, but this political adjustment does not change the longitudes of the islands. [6] [2]

The result is a technicality that shows how geographic extremes depend on definitions. Alaska is also the northernmost state, with Point Barrow at 71° 23' north. [6] [5]