'Scuse my ignorance, but do the networks own some local stations, but others are independent (and called affiliates)?
Yes, the networks used to own a majority of stations but now are down to a handful of "flagship" stations in places like NY, Chicago, LA (IE WABC, WNBC, etc.), while the bulk of stations are owned by the newer communications conglomerates.
It is actually going in a circle -- majority Network owned - to mostly independent or small groups - to majority conglomerate owned now.