The closest international airport to Sea Plains, Illinois, is Chicago O'Hare International Airport (ORD), which is one of the busiest airports in the world and offers a wide range of domestic and international flights. Another nearby option is Chicago Midway International Airport (MDW), which, while smaller than O'Hare, also provides various flight options.

For more information on airports and travel options, you can refer to the comprehensive list of airports available on Wikipedia.

Sources

List of airports in the United States - WikipediaFlights from the Midwest Region | Southwest Airlines®How to get to Plainville from 5 nearby airports - Rome2RioScott Air Force Base | Base Overview & Info | MilitaryINSTALLATIONSMiami International Airportflyreagan.com - NONSTOP DESTINATIONS - DCAPlain spotting near O'Hare? : r/ChicagoSuburbs - Reddit

Related Questions

What Airlines fly out of Peoria, IL?

What airport does Southwest fly into in Illinois?

Does Ronald Reagan airport have international flights?

Where does Southwest fly in Wisconsin?