Sidney–Richland Municipal Airport (IATA: SDY, ICAO: KSDY, FAA LID: SDY) is a mile west of Sidney, in Richland County, Montana, United States. The airport is served by one airline, subsidized by the federal government's Essential Air Service program at a cost of $3,777,579 (per year).

The Federal Aviation Administration says this airport had 2,031 passenger boardings (enplanements) in calendar year 2008, 2,766 in 2009, and 3,659 in 2010. The National Plan of Integrated Airport Systems for 2011–2015 categorized it as a general aviation airport based on enplanements in 2008 (the commercial service category requires at least 2,500 enplanements per year).