Mulino State Airport (FAA LID: 4S9) is a public airport located at Mulino, Oregon, near the city of Molalla, about 20 nautical miles (23 mi, 37 km) south of Portland with access from Interstate 205 via Oregon Route 213.

Also known as Mulino Airport, it was owned by the Port of Portland from 1988 until it was transferred to the Oregon Department of Aviation on July 1, 2009.

Mulino State Airport covers an area of 275 acres (111 ha) at an elevation of 260 feet (79 m) above mean sea level.

[1] For the 12-month period ending December 9, 2020, the airport had 21,300 general aviation aircraft operations, an average of 58 per day.

At that time there were 61 aircraft based at this airport: 57 single-engine, 2 multi-engine, and 2 glider.