Hillsboro Airport, also known as Portland–Hillsboro Airport, is a corporate, general aviation and flight-training airport serving the city of Hillsboro, in Washington County, Oregon, United States. It is one of three airports in the Portland, Oregon, metropolitan area owned and operated by the Port of Portland. Established in 1928, it is Oregon's second busiest airport at over 200,000 operations annually. HIO covers 900 acres and has three runways.