The Florida Keys Marathon International Airport

MTH originated in 1942 on 280 acres of land, with the construction of the 8,000-foot airstrip completed in 1943. Due to the timing of its construction, MTH was a part of the U.S. Navy flight programs, functioning as a Navy Outlying Field and an auxiliary airfield to Naval Air Station Key West. Initially owned by the Florida State Road Department, Monroe County petitioned the agency to turn it over to the county so it could serve as a public airport. Service at MTH began in 1959 with National Airlines, serving Marathon as a stop on the Miami to Key West route. Other commuter and regional airlines to serve MTH from the 60s to the 80s included commuter air carrier American Air Taxi, Southeast Airlines, Air Sunshine, Air Florida Commuter (via a code sharing agreement with Air Florida), Air Miami (and successor North American Airlines), Delta Connection code sharing with Comair (on behalf of Delta Air Lines), Gulfstream International, and more. In addition, American Eagle Airlines (operating codesharing flights on behalf of American Airlines) served MTH until 2000.
In contrast, in mid-2006, Delta Air Lines announced nonstop regional service between Atlanta and Marathon via its subsidiary, Atlantic Southeast Airlines. Shortly after that, Continental Airlines announced service to Marathon via Gulfstream International. In late spring 2007, the Delta service via Atlantic Southeast was replaced with a codesharing service via Freedom Airlines. Their Embraer ERJ-145 jet had better short-field performance than the Canadair regional jets employed by Atlantic Southeast. Nonetheless, by mid-summer of 2007, the service to MTH was ended due to low demand. Furthermore, in December 2008, Continental airlines began service to Fort Myers via a Cape Air codeshare, but this service ended the following year. Finally, on April 20th, 2016, a 4,200-square-foot permanent Customs and Border Patrol facility opened at MTH.

The airport is located along the Overseas Highway (US1) in Marathon. 

• MTH was featured in the "Army of Two" action video game in 2008. 
• The FBOs at MTH are Marathon General Aviation and Marathon Jet Center. 
• There is free parking at MTH and Budget, Enterprise, and Avis car rental services.