Portland International Airport is a joint civil–military airport and the largest airport in the U.S. state of Oregon, accounting for 90% of the state's passenger air travel and more than 95% of its air cargo. It is within Portland's city limits just south of the Columbia River in Multnomah County, 6 miles by air and 12 mi (19 km) by highway northeast of downtown Portland. Portland International Airport is often referred to by its IATA airport code, PDX. The airport covers 3,000 acres of land.