Most of my childhood, one. Black and white until I was about 7, then we got a color TV. That was about 1965. When the color tv died my mom moved it into the Living room because "it was too nice a piece of furniture to throw out". So we had two then, but only one that worked. When my mom passed away in 2013 I took the nice piece of furniture TV to the dump. It had been in the house nearly 50 years, only the first 10 or so was it working.
And yes, we had 4 channels. ABC, CBS, NBC and NET. NET later became PBS.