The Great Plains is a semi-arid region stretching from Canada to Mexico and westward toward the Rockies that was long known as the Great American Desert. Most early explorers and travelers thought the region to be of little value except to Indians and ranchers. Thousands of overland travelers followed the Great Platte River Road to the Golden West, but it was not until the establishment of Nebraska Territory in 1854 that pioneers could legally settle here. Even so, it was more than a decade later, after the construction of the Union Pacific Railroad, that settlement of the Plains could succeed economically. Because the Interstate highway follows the verdant Platte River Valley, the change in geography appears only gradually. Valley farmers were among the first to recognize the importance of irrigation, which has now spread to the upland Plains, making this one of the richest and most productive areas in the Great Plains today.