Which American TV western was set on a large ranch called the Ponderosa?

The Ponderosa was the fictional ranch setting for the 1959 - 1973 American western TV series "Bonanza". It was pointed out in the first season that it was a thousand square mile (640,000 acre) ranch on the shores of Lake Tahoe, nestled high in the Sierra Nevada, with a large ranch house in the center of the land area known as the 'Ponderosa'.

The "Bonanza" TV series told the story of life on the Ponderosa ranch for Cartwright patriarch Ben (Lorne Greene) and his three sons Adam (Pernell Roberts), Hoss (Dan Blocker), and 'Little' Joe (Michael Landon). The action, drama, and family life situations took place on the ranch or in nearby Virginia City, NV. The show's 14 seasons and 431 episodes made it NBC's longest-running western series.

This show focused upon the fact that men and women lived in a time where family values and the fight for justice were backed up by six-guns that always had right on their side. The guns were usually held by men from the Cartwright ranch. "Bonanza" was uniquely known for having addressed social issues (bigotry, racism, antisemitism, etc.) that were not typically covered on American television at the time.