WCSH-TV signed on December 20, 1953, from studios at the Congress Square Hotel in downtown Portland. The station was owned by the Rines family through their Maine Broadcasting System; the family had built the hotel in 1896, and established WCSH radio (970 AM, now WZAN) on the top floor in 1925. It has always been an NBC affiliate, although during the late-1950s, the station was also briefly associated with the NTA Film Network. In 1958, the Rines family acquired WTWO in Bangor from Murray Carpenter, and renamed it WLBZ-TV (after WLBZ radio, now WZON, which the family had owned since 1944). Although the two television stations were now sister stations, they remained completely separate entities. At various points, the Maine Broadcasting System also included WRDO radio in Augusta and KMEG in Sioux City, Iowa, with WCSH-AM-TV as its flagship.