Cincinnati Northern Kentucky International Airport — Cincinnati / Covington, United States

Straddling the Ohio River divide, CVG physically sits in Boone County, Kentucky, yet carries the Cincinnati name because it primarily serves that Ohio metropolis just across the water. Delta Air Lines built the field into a major connecting hub through the late twentieth century before scaling back operations in the mid-2000s, a retrenchment that reshaped the airport's identity. In the years since, cargo carriers reinvigorated the property: DHL runs a significant Americas hub from the grounds, and Amazon opened a sprawling air logistics center nearby, turning what had been primarily a passenger complex into one of the busier freight airports in the country. Four runways support round-the-clock package sorting alongside a shrinking but still meaningful roster of passenger airlines connecting the Cincinnati-Northern Kentucky metro to destinations across North America and a handful of international points beyond.