On May 30, 1959, the first F-106As were delivered to the Air Defense Command's 539th FIS at McGuire AFB in New Jersey, replacing the F-86L. However, the first operational unit was the 498th Fighter Interceptor Squadron based at Geiger AFB in Washington. This was no less than five years later than originally planned. Even then, numerous problems kept the Delta Dart from being declared fully operational until October 31, 1959. The remaining 13 squadrons were re-equipped with the F-106A by the end of 1960.
The 277th and last F-106A was delivered on July 20, 1961. The production run also included 63 F-106B two-seaters, for a total of 340 aircraft.
The F-106 served mainly in the continental United States, in Alaska, Iceland, and in Canada, but it did serve for short spells in Germany and South Korea. Although the F-106 was briefly deployed to Osan AFB in Korea in February of 1968 to provide air defense during the *Pueblo* incident, the Delta Dart never saw any combat.
From 1972 onwards, the McDonnell Douglas F-15 Eagle gradually began to replace the Delta Dart in ADC squadrons. As they were removed from Air Force service, they were passed along to the Air National Guard. First ANG unit to receive the F-106 was the 186th FIS of the Montana ANG, based at Great Falls, which took delivery of its first planes on April 3, 1972. Six ANG units flew the F-106 on Air Defense Command mission. The last Delta Dart-equipped Air Force squadron, the 119th FIS based at Atlantic City, New Jersey flew its final alert duty on July 7, 1988. The ANG units continued to fly the last few Delta Darts for only a few months longer after the USAF had relinquished the type. The last ANG to relinquish its F-106s was the 119th FIS of the New Jersey ANG, which sent its last plane to AMARC in August of 1988.