The level, unforested farming area, formerly grassland, that stretches westward from the Ohio River to the Plains region. The Prairie states include Ohio, Indiana, Illinois, and Iowa, as well as eastern North and South Dakota, northern Missouri, and southern Wisconsin, Minnesota, and Michigan, encompassing much of the Midwest. The Mississippi River flows through the center of the region, originally the Northwest Territory, whose culture has come to be considered distinctively American, with Abraham Lincoln as its typical hero. Since the pioneering period of the late 18th and early 19th century, described by James Fenimore Cooper and others, the Prairie states have become the nation's food-producing center, with a large, stable farming population, and́ with great cities like Chicago as points of distribution. Representative authors include Edward Eggleston, Booth Tarkington, James Whitcomb Riley, and other Hoosiers; Wisconsin writers such as Hamlin Garland, Zona Gale, and Glenway Wescott; O. E. Rölvaag, who wrote of Norwegian and Irish immigrants in the Dakotas; and many whose careers are in some way associated with the Chicago school, including Dreiser, Herrick, E. L. Masters, Sandburg, Lindsay, Sinclair Lewis, Sherwood Anderson, and Hemingway. The paintings of Grant Wood are expressive of the life of rural Iowa; Louis Sullivan and J. W. Root were the first of the Chicago school in architecture that has influenced urban construction by introducing the skyscraper; and Frank Lloyd Wright's “Prairie style” of domestic architecture was designed to be appropriate to the Midwestern landscape.