When did B/W broadcasts stop?

[frenchy]

Since even today someone can broadcast a BW picture or show over a color signal, maybe some more questions to ask would be:
"what was the last major network affiliate to completely eliminate broadasting of a non-color-encoded signal?"
"what was the last low-budget local (non-major-network) channel, uhf or vhf, to broadcast a black and white only signal?
"what was the last major network television show that was produced in black and white?"

The thing about the news not being completely in color could just be a factor of when they had gotten rid of all their old black and white film cameras and switched to color film....then switched to color videotape.