The airfield was originally built in 1941 for RAF Bomber Command, then expanded for use by American heavy bombers during 1942. Kimbolton was assigned United States Army Air Force Eighth Air Force. It was given designation USAAF Station 117.
The airfield was opened in 1942 and was first used by the United States Army Air Force Eighth Air Force 91st Bombardment Group (Heavy), arriving from Walla Walla AAF, Washington during September.
The 91st was assigned to the 1st Combat Bombardment Wing of the 1st Bombardment Division. Its tail code was Triangle-A. Its operational B-17 Flying Fortress squadrons were:
322d Bomb Squadron (LG)
323d Bomb Squadron (OR)
324th Bomb Squadron (DF)
401st Bomb Squadron (LL)
The 91st stayed at Kimbolton only a few weeks, because the runways at Kimbolton were not strong or long enough for the safe operation of Fortresses. The group then was transferred to RAF Bassingbourn on 14 October.