Snowmobiles are not allowed on public highways, except to make crossings, and never on interstates or freeways. They can be ridden on unplowed city streets and along rights of way in counties where the board of supervisors has voted to allow such snowmobile use. To drive on streets or county roads, you must have a valid driver's license and proof of insurance. Check local ordinances before you go.
Check out these Council Bluffs, IA ATV/OHV resources: