Lots of my ancestors arrived on the Iowa prairie before and after it became a state in 1846. A lot more were born the state. For the early arrivals and native American Indians Iowa was prairie. The yellow areas on this map of Iowa- 1830-50 are prairie, nothing but prairie. Green areas are woodland. See the map and the Remnant Prairie article here.
In Cedar Rapids, Iowa there’s a tiny restored prairie. Millions of things are living and growing there.