The first telecast of Bonanza was on September 12, 1959. The last telecast was on January 16, 1973. The NBC program ran mainly on Saturday nights from 7:30 to 8:30 p.m.
The Cartwright family, headed by the patriarch dad, Ben Cartwright, was made up of four sons. Lorne Greene played Ben Cartwright, Michael Landon was Little Joe Cartwright, Dan Blocker was "Hoss" Cartwright (until he died in 1972), and Pernell Roberts was Adam Cartwright (until he left the program in 1965). They ran the Ponderosa Ranch, supposedly located in Virginia City, Nevada during the Civil War. The program was not a "shoot-em-up" Western. The story lines were more about the relationships among the characters.
Bonanza remained high in the ratings until Dan Blocker died. After that the ratings dropped, and the program came to an end.