The station first signed on the air as WWDT on October 23, 1946 for one day of demonstrative programming; regular programming commenced on March 4, 1947. It was the first television station in Michigan and the tenth station to sign on in the United States overall. The station was originally owned by the Evening News Association, parent company of the "Detroit News", along with WWJ radio (AM 950 and FM 97.1, now WXYT-FM). On May 15, 1947, the television station changed its call letters to WWJ-TV to match its radio sisters. Channel 4 has always been an NBC affiliate owing to WWJ radio's longtime affiliation with the NBC Red Network, but also aired some programs from the DuMont Television Network prior to WJBK-TV (channel 2)'s sign-on in October 1948.