Extreme points of the United States
This is a list of the extreme points of the United States, the points that are farther north, south, east, or west than any other location in the country. Also included are extreme points in elevation, extreme distances, and other points of peculiar geographic interest.
There are three methods for reckoning the eastern and western extremes of the United States.
One method is to use the Prime Meridian as the dividing line between east and west. This meridian running through Greenwich, London, is defined as zero degrees longitude and could be called the least eastern and least western place in the world. The 180th meridian, on the opposite side of the globe, is therefore the easternmost and westernmost place in the world.
Another method is to use the International Date Line as the easternmost–westernmost extreme. On the equinox, the easternmost place would be where the day first begins, and the westernmost is where the day last ends.
Still another method is to first determine the geographic center of the country and from there measure the shortest distance to every other point. All U.S. territory is spread across less than 180° of longitude, so from any spot in the U.S. it is more direct to reach Point Udall, U.S. Virgin Islands, by traveling east than by traveling west. Likewise, there is not a single point in U.S. territory from which heading east is a shorter route to Point Udall, Guam, than heading west would be, even accounting for circumpolar routes. The two Udalls for whom the two Points are named were brothers, Mo Udall in Guam and Stewart Udall in the Virgin Islands.
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