Veterans Airport of Southern Illinois (IATA: MWA, ICAO: KMWA, FAA LID: MWA), also known as Williamson County Regional Airport, is five miles west of Marion, in Williamson County, Illinois, United States. The airport is owned by the Williamson County Airport Authority. It sees one airline, subsidized by the federal government's Essential Air Service program at an annual cost of $2,562,819 or $141 per passenger. On November 11, 2016 during the grand opening ceremony for the new terminal, the airport was renamed to "Veterans Airport of Southern Illinois" to honor veterans and better reflect the regional nature of the airport.

Federal Aviation Administration records say the airport had 3,631 passenger boardings (enplanements) in calendar year 2008; 3,399 in 2009; and 8,047 in 2010. The National Plan of Integrated Airport Systems for 2011–2015 categorized it as a non-primary commercial service airport (between 2,500 and 10,000 enplanements per year).

It is the tenth busiest of the 12 commercial airports in Illinois.