At a Glance

The imaginary line was metaphorically "drawn in the dirt" byAmerican geologist and explorer John Wesley Powellin 1878.The line appears to be moving east, which could have big impacts on farming and other pursuits, researchers say.

The 100th meridian, which bisects the Great Plains and separates the aridwestern states from the moister eastern states, may be shifting as a result of climate change, say.

The imaginary line, metaphorically "drawn in the dirt" byAmerican geologist and explorer John Wesley Powelin 1878, transects Texas, Oklahoma, Kansas, Nebraska and the Dakotas in the United States, and continues up into Canada's Manitoba.

Powell used the line to try to convince Congress toplan water and land-management districts that crossed state lines based on environmental constraints. His suggestions were met with backlashbecause legislators feared interstate districts would limit growth. Considering the water issues facing western states today, perhaps legislators should have taken Powell's theories under consideration.

A team of researchers from theLamont–Doherty Earth Observatory of Columbia University decided to take a new look at Powell's divide. In one study published in 2017 in the journal of the American Meteorological Society, the team confirmed that based on population and agriculture trends that have developed on oppositesides of the divide.

In a second study published in March in the AMS journal, the researchers concluded that the line appears to be , which could have bigimpacts on farming and other pursuits.

"Adjustment to changing environmental conditions would cause farm size and rangeland area to increase across the plains and percent of cropland under corn to decrease in the northern Plains as the century advances," the study says.

Richard Seager, a climate scientist at Columbia University’sLamont-Doherty Earth Observatoryand lead author of the two papers, calls this type of study“psychogeography” because it studies how theenvironment affects human decisions.

“Powell talked eloquently about the 100th meridian, and this concept of a boundary line has stayed with us down to the current day,” said Seager. “We wanted to ask whether there really is such a divideand whether it’s influenced human settlement.”

The researchers noted that the divide described by Powell played out in how the land was settled and cultivated, including the sharp decline in population west of the line. The once "luxuriant grasslands" described by Powell for the eastern half of the nation has been replaced by cornfields, but the theory was correct, the researchers pointed out.

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The dividealso determines what crops have been cultivated, with moisture-lovingcorn grown in the eastern states andwheat in the West.

The scientists concluded that a change in weather patternsin response toclimate change indicates the imaginaryline has shifted east about 140 miles towards the 98th meridian since 1980. In Texas, that means the divide has shifted from Abilene towards Fort Worth, according to the study.

Rainfall has not changed much in the northern Plains as a result of climate change, but rising temperatures have increased evaporation from the soil. Meanwhile, in the southern Plains, wind patterns are causing a drop in rainfall.

The researchers say itislikely that Powell's divide will continue to shift east as the warming planet adapts and weather patterns continue to change.

Their hope is that the results of the study will contribute to policy decisions that will aid with the "adaptation to changing conditions and avoid the negative effects of surprises followed by crises and social and economic disruption."