The traffic to and from Iowa City is always minimal so even the distant airports are reasonable travel times.

The closest and best option is CID: The Eastern Iowa Airport (Cedar Rapids-Iowa City): Distance 22 miles (25 minutes)

United, Delta, American, Allegiant , Frontier

Additional options are listed below

MLI: Quad Cities Airport (Moline, IL): 64 miles (1 hour 5 minutes)

Airlines: United, Delta, American

DSM: Des Moines, Iowa: 126 miles (1 hour 45 minutes)

United, Delta, American, US Airways, Frontier, Southwest, Allegiant

PIA: Peoria, Illinois: 150 miles (2 hours 20 minutes)

Allegiant, United, Delta, American

ALO: Waterloo, Iowa: 88 miles (1 hour 20 minutes)

Only American

DBQ: Dubuque, Iowa: 97 miles (1 hour 35 minutes)

Only American

Chicago is a major hub and it may be a reasonable option if you want to rent a car. The drive is very easy from both Midway and O’Hare. 

ORD: O’Hare: 230 miles (3 hours 15 minutes)

MDW: Midway: 236 miles (3 hours 30 minutes)