I thought Piedmont served ILG. Does anyone have an old timetable?
Also, I still am not clear why TTN-CLT and ACY-CLT would not work if operated on an RJ.
OK, kids, here's the straight poop: Well into the 1970s, both Allegheny (pre-US) AND Eastern served ILG. Both had dropped it by the start of deregulation in December 1978.
EAL had DC-9s into Wilmington until the mid-70s, when the CAB finally allowed them to drop the airport from their schedule.
AL continued serving ILG a wee bit longer, until they retired the last of their Convair 580s in the 1977-78 timeframe. AFAIK, AL did not ever schedule DC-9s into ILG.
Rather surprisingly, when they dropped ILG they dropped it totally, rather than turn over the service to one of the early Allegheny Commuter companies like Suburban or Ransome.
Further ILG history: Prior to WWII, Wilmington had no scheduled air service. The only airfield was the private DuPont Airport, north of town.
Like so many other fields, the current New Castle County Airport was constructed for military use during the war. Following the war, it was turned over to the county, and three of the then-"Big Four" carriers began ILG service during the late '40s: AA. EA, and TW.
TW pulled out within ten years, turning their route authority over to then-tiny Allegheny (originally All-American).
American hung on until 1960, while Eastern, as stated above, stayed around until the mid-70s.
...and that's....the rest...of the story!