KFJB Marshalltown, IA. Years ago, it was a split between KFJB and WFXN Moline, IL (formerly WQUA). You could clearly hear both signals; both are about 65 miles away. Now, I think the WFXN signal has degraded and I think hearing it is a rarity.
WQUA used to be my competitor. And a very tough competitor at that. Everything about their operation during the mid-70s (and the years preceeding) was first-class. Beautiful building, state of the art studios/equipment, and great talent. Part of the deal was getting all they could out of their 1kw signal. Around Cedar Rapids and Iowa City WQUA more than held their own against KFJB, which also got out pretty well. In the opposite direction (southeast), WQUA also did well "versus", WJBC from Bloomington, IL....another class act (and very profitable).
BTW, WQUA is also the "alma mater" of Hall of Fame baseball announcer, Milo Hamilton.