Midwest Designer/Developer Salary

I’m about to receive a job offer for a website designer/developer position at a creative agency. What should I expect my salary to be? Most of the work would be custom WordPress themes, but I would also be working alongside the programming team to do backend dev work since I would be one of the few employees who know how. Their lead designer/developer is moving to a creative director role, and it sounds like I would essentially be taking over her previous responsibilities but not technically have the “lead” title. I currently freelance and have never had a FT job in this field. I previously worked in marketing and have other agency experience, and I have 5 years of experience freelancing full time as a website designer/developer. The job is in a town of about 40k people in Iowa, so it’s impossible to research salaries for similar positions. I want to have an idea of what to expect! TL;DR: What would be an appropriate salary for a website designer/developer with 5 years of experience at a creative agency in the midwest?