ABC affiliate WJZ-TV (now WABC-TV) in New York City went on the air August 10th, 1948. According to C.E. Hooper, from 7-10:30PM that night the station drew a 29.3 rating and a 52.3 share of the audience. During that period, 56.5% of television sets in the area–some 200,000–were in use.
Doing a little math, that means about 113,000 sets were in use from 7-10:30PM on August 10th, 1948 and roughly half were watching WJZ-TV. Not bad for a new station.
References:
“Radio and Television.” New York Times. 18 Aug. 1948: 50.
More impressive because not everyone had a TV set back then.
The station’s original transmitter was atop the Hotel Pierre on Fifth Avenue across from the southeasternmost tip of Central Park, not to be moved to “the top of the Empire State Building in midtown Manhattan” (per many a WJZ/WABC staff announcer’s sign-off spiel for nearly three decades) until early 1951.
Its 75th anniversary is coming up soon.