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The 100th Meridian

In 1878, a geologist and explorer named John Wesley Powell drew an invisible longitudinal line through Texas, Oklahoma, Kansas, Nebraska, and the Dakotas. It’s called the 100th meridian, the boundary between the humid eastern United States and the arid Western plains.

Today, scientists are looking again at the 100th meridian. Richard Seager is a climate scientist at Columbia University’s Lamont Doherty Earth Observatory. He says because of climate changes, the longitudinal line has been shifting eastward. It’s only by a few degrees, but there will be a noticeable change.

"Both west of the meridian and east of the meridian, aridity will be increasing which means that the arid west will encroach towards the east. But even in the east and more humid parts, there will be rising aridity as well,'  says Seager. "So, the whole Plains will be feeling these changes."

Seager expects the aridity will continue moving eastward throughout the 21st century, and eventually mean large-scale changes in agriculture.

"You would expect the corn cultivation to be increasingly restricted to the east, and that would create some space for expansion of wheat and rangeland," he says. "But of course, that’s just what climate change would do, and in reality, an awful lot of other things happen too and farmers will make some kind of adjustment based on maximizing their returns."

Read more about the shift of the 100th meridian

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