Almost anywhere outside of a major city will allow you to live on 55k a year comfortably. You would have to be diligent about budgeting, but this is doable. I lived in Saint Louis on 48k a year as a single guy, but i was also spending a lot on rent because i lived near the city center.

My brother lives in Saint Joseph, MO and is married and their combined income was close to the 50k mark. So this is doable.