Interstate Aircraft and Engineering Corporation was a small American aircraft manufacturer in production from April 1937 to 1945, based in El Segundo, California. In 1940 they developed the Cadet, a 2-seat monoplane. The Model S-1B was developed into the XO-63, later redesignated to the XL-6. A total of 259 of the XO-63/L-6/L-8 series were built for the US Army Air Forces. The company also manufactured a trainer for the US Navy which was developed in only nine months, from the first blueprints to first flight of the prototype. The company also manufactured bomb shackles, machine gun and cannon chargers, hydraulic actuators, and other aircraft components.
In 1945, after manufacturing over 700 light aircraft, Interstate sold its line of aircraft to the Harlow Aircraft Company of Alhambra, California. Company president, Don P. Smith stated that the firm would require all available space formerly used in the production of aircraft for post-war manufacturing of soft drink dispensing machines, vacuum cleaners, and a line of small gasoline engines.
The company changed its name to Interstate Engineering to reflect the change in business strategy. However, within a few years, Interstate also began producing helicopter fuselages for United Helicopters, Inc. of Palo Alto, California, and had contracts with Douglas Aircraft Company, the US Navy and US Air Force.
Harlow Aircraft sold the manufacturing rights for the Cadet aircraft to Call Aircraft Company of Afton, Wyoming, in 1945. In the 1960s, newly formed Arctic Aircraft purchased the rights, and currently produces an upgraded version of the aircraft as the Arctic Tern.