Back in the day (i.e. the 1970s), NBC and CBS alone carried the Rose Bowl Parade. I want to say NBC carried either a pre-parade show at 10 a.m. Eastern or some other parade (they also carried the Orange Bowl Jamboree Parade when the network had the game rights, but the parade was always at night). I think CBS might have had a short East Coast parade as well.
Parade coverage would run from 11 a.m. to 1 or 1:30 p.m., just like today. CBS would then switch to the Cotton Bowl; NBC usually had the Rose Bowl game in the late afternoon, Orange Bowl game in the evening, and another (Fiesta Bowl, perhaps) in the early afternoon.
I know ABC didn't pick up parade coverage until at least 1990, the same year the game rights moved over to them.
O.B. Game Shows: I also recall at least one year (1991?) when all but one of the commercial New York stations had the Rose Bowl parade: WCBS, WNBC, WABC, WNYW (Fox, co-hosted by Alex Trebek), and WPIX (KTLA's feed, co-hosted by Bob Eubanks).
Thanksgiving Day, the day after Thanksgiving, and New Year's Day are always rife with game show pre-emptions.