1973: 'Bonanza' Finishes its 14-Season Run
This amazingly popular series premiered in 1959, as television's first Western to be televised in color. NBC's parent company, RCA, wanted to sell color TVs, and producing Bonanza in full color turned out to be a bonanza indeed. In addition to all the TV sales it sparked, Bonanza also was TV's highest-rated series in the mid-sixties, and held on long enough to avoid cancellation until this day in 1973.
Like Gunsmoke, Bonanza has a very moral center, lashing out against bigotry and even treating most Native American characters, and Mexicans and blacks, with a then-unusual sense of decency. The scripts were sometimes hokey, but the casting saved a lot of stories.
Lorne Greene's patriach, Pa Cartwright, was a TV icon, and his original "my three sons" — Pernell Roberts's brooding Adam, Dan Blocker's gentle-giant Hoss, and Michael Landon's Little Joe — accounted for the show's popularity and durability.
—Excerpted from Dictionary of Teleliteracy: Television's 500 Biggest Hits, Misses and Events