It's definitely too soon for you to worry about residency if you don't yet have an acceptance to medical school. Perhaps you have an acceptance already though.
If your husband is vocal and supportive about moving, that's great. And aren't Des Moine and Iowa City like, 2 hours from each other? I think most of us would consider 2 hours "Close to home" for residency purposes.
Additionally, I feel the need to state that only ~50% of people even get their first choice for residency. Your attitudes about moving may change when it comes time for residency, and that you'll likely want to interview at somewhere around 15 or so programs. It doesn't do well to enter interview season with the mindset that you ABSOLUTELY must get into THIS ONE program.