WCBS 880 KHz is a "clear channel" station running 50 KW (the AM broadcast limit) to an Omni-directional antenna. It has no repeaters.
In 1941, the FCC designated 60 broadcast stations (1920's & 30's) as Class I (now Class A) licensees, to cover as much of the US landscape as possible, so no other station within a specific geographic radius will re-use their frequencies.
Examples are WBZ 1030 Boston; WFAN (previously WEAF, then WNBC) 660, WABC 770, & WCBS 880 New York [old radio network flagships], KYW 1060 & WPHT (formerly WCAU) 1210 Philadelphia, KDKA 1020 Pittsburgh, and WBBM 780 & WLS 890 Chicago.
When skip is running in the summer,