Winnemac is a fictional state in the United States invented by writer Sinclair Lewis. The town of Zenith provides the setting for Babbitt, Arrowsmith, Dodsworth, and other novels by Lewis. It is distinguished from Gopher Prairie which is the setting of the novel Main Street.

In Arrowsmith, Lewis describes Winnemac thus:

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.

The University of Winnemac is at Mohalis, fifteen miles from Zenith. There are twelve thousand students; beside this prodigy Oxford is a tiny theological school and Harvard a select college for young gentlemen. The University has a baseball field under glass; its buildings are measured by the mile; it hires hundreds of young Doctors of Philosophy to give rapid instruction in Sanskrit, navigation, accountancy, spectacle-fitting, sanitary engineering, Provencal poetry, tariff schedules, rutabaga-growing, motor-car designing, the history of Voronezh, the style of Matthew Arnold, the diagnosis of myohypertrophia kymoparalytica, and department- store advertising. Its president is the best money-raiser and the best after-dinner speaker in the United States; and Winnemac was the first school in the world to conduct its extension courses by radio.