Not many persons will remember it today. I did not know about it at all. I was not born when the first soap opera finished it's plot. It was favourite entertainment of the housewives from 1933 to 1960. And I was born in '61. Fortunatelly, it's possible to listen to the registrations of those radio dreams of many women. The title of the first radio soap opera was "Ma Perkins". If you listen to this record, you will understand without explanations why these transmissions were called "soap" operas.
I do not know if the «Search for tomorrow» was the first TV soap opera (1951-1986 more or less). I even can't believe that such a "work" could live so long.
These two transmissions had other 2 primacies: main actresses partecipated on the "show" for 27 and 35 years (well, it can be not precise, maybe, I don't know...)
The longest soap opera was Indian "Mahabharat"
And the most numerous stuff, 300 000 persons, was in the film "Three Kingdoms" (China), in 1996.