Blue Ash is a city in Hamilton County, Ohio, United States, and an inner suburb of Cincinnati, which is located just to the south. The population was 12,513 at the 2000 census. According to the United States Census Bureau, the city has a total area of 7.7 square miles (20 km2), of which 7.7 square miles (20 km2) of it is land and 0.13% is water. Blue Ash can be reached by Interstate 71 to the east, Interstate 275 to the north, and Ronald Reagan Cross County Highway to the south. A public airport, the Blue Ash Airport, is operated by the city. The 123rd Air Control Squadron of the Ohio Air National Guard is based at the airport.