Wittman Regional Airport — Oshkosh, United States

Wittman Regional Airport (OSH) in Oshkosh, Wisconsin, is best known worldwide as the site of the Experimental Aircraft Association's AirVenture Oshkosh, an enormous annual fly-in that briefly transforms it into one of the busiest airports on Earth, with thousands of aircraft arriving over a single week. Outside of that late-July event, OSH functions as a modest regional airport supporting general aviation, flight training, and limited commercial service. The airport's air traffic control operation during AirVenture is famously intense, employing specialized visual approach procedures to manage extraordinary volumes of small aircraft simultaneously. Named after aviation pioneer Steve Wittman, OSH holds a unique place in American aviation culture despite its otherwise quiet year-round operations.