Many nineteenth century European-Americans did not see the prairie’s abundance and beauty as Native Americans did, but instead treated it first as a barrier on the way to destinations farther west such as Oregon, California, and Utah. As thousands passed across the plains, their animals devoured the grasses, their wagons cut deep paths, and they brought diseases to Native Americans who had no resistance. The movement of so many people also disrupted the migration routes of animal herds that Native Americans depended on for food, tools, clothing, and housing, causing some animals to disappear completely and others to retreat into ever shrinking habitats. The prairie wolf and Audubon bighorn sheep are extinct, while bears, elk, moose, and antelope appear only rarely, and the area’s bison no longer roam free but live on ranches. After Nebraska opened to homesteading, settlers gradually reached the Scotts Bluff area, where modern irrigation from the North Platte River watered crops and cattle, trees were planted as windbreaks, and the prairie was transformed into a vital part of the nation’s food production.