100°
100th meridian west

The meridian 100° west of Greenwich is a line of longitude that extends from the North Pole across the Arctic Ocean , North America , the Pacific Ocean , the Southern Ocean , and Antarctica to the South Pole .

The 100th meridian west forms a great circle with the 80th meridian east .

From Pole to Pole

Starting at the North Pole and heading south to the South Pole , the 100th meridian west passes through:

Co-ordinates Country, territory or sea Notes
Arctic Ocean
Canada Nunavut Meighen Island
Peary Channel
Canada Nunavut Ellef Ringnes Island
Unnamed waterbody
Canada Nunavut Berkeley Islands and Bathurst Island
Parry Channel
Canada Nunavut Prince of Wales Island
M'Clintock Channel
Larsen Sound Passing just east of Gateshead Island , Nunavut , Canada (at )
Victoria Strait
Canada Nunavut Royal Geographical Society Islands
Queen Maud Gulf Passing just east of Hat Island , Nunavut , Canada (at )
Canada Nunavut
Manitoba — from
United States North Dakota
South Dakota — from
Nebraska — from
Kansas — from
Oklahoma — from
Texas / Oklahoma border — from
Texas — from
Mexico Coahuila
Nuevo León — from
Tamaulipas — from
San Luis Potosí — from
Tamaulipas — from
San Luis Potosí — from
Guanajuato — from
Querétaro — from
Mexico State — from
Guerrero — from
Pacific Ocean
Southern Ocean
Antarctica Unclaimed territory

United States

In the United States the meridian 100° west of Greenwich forms the eastern border of the Texas panhandle with Oklahoma (which traces its origin to the Adams-Onís Treaty in 1819 which settled the border between New Spain and the United States between the Red River and Arkansas River ). Dodge City, Kansas lies exactly at the intersection of the Arkansas River and the 100th meridian.

In the central Great Plains , the meridian roughly marks the western boundary of the normal reach of moist air from the Gulf of Mexico , and the approximate boundary (although some areas do push the boundary slightly farther east) between the semi-arid climate to the west and the humid continental (north of about 37°N ) and humid subtropical (south of about 37°N ) climates to the east. The type of agriculture west of the meridian typically relies heavily on irrigation . Historically the meridian has often been taken as a rough boundary between the eastern and western United States. White settlement, spreading westward after the American Civil War , settled the area around this meridian during the 1870s.

A sign across U.S. Highway 30 in Cozad, Nebraska , marks the place where the 100th meridian intersects with the routes of the Oregon Trail , Pony Express , transcontinental railroad , and the Lincoln Highway .

Wallace Stegner 's Beyond the Hundredth Meridian (1954), is a biography of John Wesley Powell , an explorer of the American West.

The song " At the Hundredth Meridian " by The Tragically Hip is about the 100th meridian west, specifically in Canada, and how it has traditionally been considered "where the great plains begin."


Preceded by
99th meridian west
100th meridian west

forms a great circle with

80th meridian east

Succeeded by
101st meridian west

See also