Sinclair Lewis set most of his greatest novels in the fictitious city of Zenith. Chapter 2 of Arrowsmith explains:

The state of Winnemac is bounded by Michigan, Ohio, Illinois, and Indiana, and like them it is half Eastern, half Midwestern. There is a feeling of New England in its brick and sycamore villages, its stable industries, and a tradition which goes back to the Revolutionary War. Zenith, the largest city in the state, was founded in 1792. But Winnemac is midwestern in its fields of corn and wheat, its red barns and silos, and, despite the immense antiquity of Zenith, many counties were not settled till 1860.