Settlement of the Great Plains, beginning in earnest in the mid-1800s, triggered one of the largest ecological transformations in North American history. Settlers converted vast stretches of native grassland into cropland, hunted keystone species nearly to extinction, drained ancient water reserves, and introduced invasive plants that continue to reshape the landscape today. At least 80% of the original grasslands are now gone, and the consequences ripple through soil, water, wildlife, and climate.
Loss of Native Grasslands
Before European-American settlement, the Great Plains stretched from Texas to the Dakotas as a continuous sea of grass, divided roughly into tallgrass prairie in the east, mixed-grass in the center, and shortgrass in the drier west. These grasslands had developed over thousands of years, sustained by grazing animals, periodic fire, and drought cycles. Settlers saw them as empty land waiting for the plow.
The tallgrass prairie was hit hardest. Its deep, fertile soils made it ideal for corn and wheat, and today 99% of the original tallgrass prairie is gone. Across the Great Plains as a whole, agricultural cultivation, development, and invasive species have destroyed at least 80% of native grasslands. That conversion didn’t just change the view. It dismantled an ecosystem. Prairie grasses have root systems that can reach 10 feet deep or more, binding soil, cycling nutrients, storing carbon, and absorbing rainfall. Removing them set off a chain of environmental problems that settlers didn’t anticipate and that persist more than a century later.
Soil Destruction and the Dust Bowl
Native grasses held the Great Plains together, literally. Their dense root networks anchored topsoil that had built up over millennia. When settlers plowed millions of acres in the late 1800s and early 1900s, they exposed bare soil to wind and rain. The consequences were manageable in wet years. Then the drought of the 1930s arrived.
The Dust Bowl remains one of the worst environmental disasters in American history. Strong winds stripped an average of 480 tons of topsoil per acre from degraded farmland. In 1935 alone, an estimated 850 million tons of topsoil blew away from more than 4 million acres. Roughly 10 million acres lost their upper five inches of soil entirely, and another 13.5 million acres lost about two and a half inches. That topsoil had taken centuries to form. Its loss degraded soil productivity, filled the air with choking dust clouds that traveled as far as the East Coast, and forced tens of thousands of families to abandon their farms.
Even after the Dust Bowl, the damage wasn’t fully reversed. Government conservation programs introduced windbreaks and contour plowing, but much of the original soil richness was permanently lost. Erosion remains a concern on Great Plains farmland today, especially in areas where conservation practices have been relaxed to plant more crops during periods of high grain prices.
Collapse of Bison and Other Wildlife
Before settlement, an estimated 30 to 60 million bison roamed the Great Plains. They were the ecological engine of the grassland system, grazing in patterns that promoted plant diversity, fertilizing soil, and creating wallows that collected rainwater for other species. By the 1890s, fewer than 1,000 bison remained. Some estimates put the low point at just 300 animals.
The collapse was driven by several forces at once. Railways opened the interior to commercial hunters. An international market for buffalo hides made killing profitable at industrial scale. The U.S. military actively encouraged the slaughter as a strategy to undermine Plains Indian nations that depended on bison. Diseases introduced by domestic cattle, competition from livestock herds, and drought compounded the decline. What had been the most abundant large mammal on the continent was pushed to the edge of extinction in roughly 60 years.
Bison weren’t the only casualties. Prairie dogs, whose extensive burrow systems aerated soil and provided habitat for dozens of other species, were systematically poisoned as agricultural pests. Black-footed ferrets, which depended on prairie dog colonies, nearly vanished. Grassland birds like the greater prairie chicken lost nesting habitat as native grass was plowed under. The removal of these interconnected species weakened the grassland ecosystem’s ability to function and recover from disturbance.
Draining the Ogallala Aquifer
The western Great Plains receives relatively little rainfall, and settlers quickly learned that dryland farming was unreliable. The solution, starting in the early 1900s and accelerating dramatically after World War II, was to pump groundwater from the High Plains aquifer system, commonly called the Ogallala Aquifer. This massive underground water reserve stretches beneath parts of eight states, from South Dakota to Texas, and accumulated over millions of years.
Irrigation transformed the region into one of the most productive agricultural areas in the world, but it has drawn water far faster than rainfall can replenish it. In some areas, water levels have dropped more than 100 feet since large-scale pumping began. In others, the saturated thickness of the aquifer, the actual water-bearing layer, has been reduced by more than half. Parts of western Kansas and the Texas Panhandle are approaching the point where pumping is no longer economically viable because so little water remains.
The depletion extends beyond farming. Streams and rivers fed by the aquifer have dried up or shrunk, reducing habitat for fish and riparian wildlife. Springs that once supported wetland ecosystems have gone silent. Communities that rely on the aquifer for drinking water face difficult long-term questions about sustainability.
Changes to Local Climate
Converting grassland to cropland didn’t just change what grew on the surface. It altered the way the land interacts with the atmosphere. Research from the University of Nebraska has documented how this transformation affects temperature, moisture, and energy balance across the northern Great Plains.
Native grasses and agricultural crops reflect and absorb sunlight differently. Cropland, especially irrigated fields, tends to have higher reflectivity and releases more moisture into the air through evaporation. Modeling studies suggest that the shift from natural grass to irrigated agriculture increased soil water storage in the root zone and boosted the amount of energy transferred to the atmosphere as moisture rather than heat. In temperate regions like the Great Plains, this land-use change may have reduced summer temperatures by up to 0.7°C in some areas. That might sound beneficial, but it also altered precipitation patterns and the frequency of convective storms, the kind of heavy, localized rainfall events common in summer.
These climate feedbacks are subtle but significant. Changes in when and how much rain falls affect crop yields, erosion rates, and the survival of remaining native plant communities. The Great Plains climate that exists today is not the same one that existed before the plow arrived.
Invasive Species and Altered Fire Cycles
Settlement introduced non-native plant species that continue to reshape Great Plains and western grassland ecosystems. Cheatgrass is one of the most damaging. Originally from Eurasia, it likely arrived in contaminated seed stocks and livestock bedding in the late 1800s. It thrives on disturbed ground, exactly the kind of conditions that settlement created through plowing, overgrazing, and soil disruption.
Cheatgrass outcompetes native plants by germinating earlier in the season, grabbing moisture and nutrients before perennial grasses emerge. More critically, it changes fire behavior. Native grasslands evolved with periodic fire, but cheatgrass dries out earlier and burns more readily, creating a cycle of more frequent fires that kill native shrubs and perennial grasses while favoring cheatgrass regrowth. Each fire shifts the balance further toward cheatgrass dominance. This cycle reduces biodiversity, lowers rangeland productivity for both wildlife and livestock, and alters carbon storage, nutrient cycling, and water infiltration across millions of acres.
Other invasive species followed similar paths. Leafy spurge, Canada thistle, and various brome grasses spread across degraded rangeland, forming monocultures that support far fewer insects, birds, and mammals than native prairie. Once established, these invasions are extremely difficult and expensive to reverse, making them one of the most persistent environmental legacies of Great Plains settlement.