Finish crossing the state of Iowa, cross the Missouri River, and enter Nebraska at Nebraska City. Nebraska City is the place where Arbor Day started. If I had not had to go out-of-my-way on my first day of riding in Iowa, I would likely have crossed the state with only three days of riding instead of four.
My overall impression of Iowa is pleasant if not particularly memorable which was okay with me at the time and today. Iowa was easy, pleasant riding.