Conventional wisdom states that it was when it first aired network programming on 4/19/1948, a few months before its own flagship station, WJZ-TV, went on the air. But while I was researching WBKB Chicago, I found that it had either sponsored or produced programming for WBKB, WRGB Schenectady, WFIL-TV Philadelphia, and Dumont's WABD New York and WTTG Washington (which were connected and aired early ABC programming), starting in 1946. Of course, other than WABD and WTTG, none of these stations were connected via coax yet. My source was Broadcasting Magazine for 7/15/46.
Another issue of Broadcasting, 11/11/46, mentions ABC producing hockey games in Chicago (WBKB) and Philadelphia (WFIL). Of course, it would have had to have been minor league hockey in Philly, since the NHL Flyers didn't join the league until 1967.
I knew that ABC in New York produced some shows that aired on Dumont until WJZ-TV was ready to go, but I wasn't aware of their earlier programming efforts. You learn something new every day.
Another issue of Broadcasting, 11/11/46, mentions ABC producing hockey games in Chicago (WBKB) and Philadelphia (WFIL). Of course, it would have had to have been minor league hockey in Philly, since the NHL Flyers didn't join the league until 1967.
I knew that ABC in New York produced some shows that aired on Dumont until WJZ-TV was ready to go, but I wasn't aware of their earlier programming efforts. You learn something new every day.