Probably not the farthest reported...I grew up in the foothills of Los Angeles, near Glendale - in the 1960's - prior to cable. The mountains blocked us from most of the LA stations, which had transmitters on Mt. Wilson. But San Diego stations - 145 miles away - came in clearly, most of the time - So in those days, they were KOGO Channel 10 (NBC), KFMB Channel 8 (CBS), and XETV Channel 6 (ABC). Also Channel 12 from Tijuana, the first Spanish language station I ever watched...Los Angeles didn't have one yet.
We could also occasionally get KEYT Channel 3 from Santa Barbara - about 90 miles in the other direction (north) which in those days, ran programming from all 3 networks.