Whiteside County Airport, also known as Jos H Bittorf Field, is a public airport located in Sterling/Rock Falls, Illinois, USA. The airport is owned and operated by the Whiteside County Board, and serves the surrounding area.

The airport was first established in the 1920s, when it began as an airstrip for the Illinois Central Railroad. At the time, the airport was a small, open grass field for private aircraft. As the demand for aviation services grew, the airstrip was developed into a formal airfield, and it has been operational ever since.

The airport was named after Jos H Bittorf, an American aviator and World War I flying ace. He was born in Whiteside County, and he was the first aviator from the county to fly in a combat mission during the war. In honor of his service, the airport was named after him.

The airport code, SQI, was assigned by the International Air Transport Association (IATA). It is derived from the airport's name, which is an acronym for "Sterling/Rock Falls International".

Whiteside County Airport operates on a daily basis, with several flights to and from major cities in the Midwest region. Airlines that serve the airport include American Airlines, Delta Airlines, United Airlines, and Air Choice One.

Whiteside County Airport has a single runway, and an air traffic control tower. Other amenities include a terminal building, rental car services, aircraft maintenance and fueling services, and a flight school. The airport also plays host to several events throughout the year, such as air shows and fly-ins.

Whiteside County Airport is a vital asset to the local community, providing employment opportunities, leisure activities, and general aviation services to the area. It plays an important role in connecting Whiteside County to the rest of the world, and it is a testament to the legacy of Jos H Bittorf.