In the mid 1950s quiz shows moved to prime time and the jackpots got bigger. Big money shows like the $64,000 Question, Tic Tac Dough, and Twenty-One garnered huge ratings. The format changed a bit with contestants choosing questions on a specific topic and returned each week to answer progressively more difficult questions. Here are videos of these shows:
Here's the intro to The $64,000 question with handsome Hal March:
This segment of Twenty-0ne, hosted by Jack Barry, figured prominently in the scandals that brought the demise of big cash game shows.
In August of 1958, the cheating in these game shows was exposed and a scandal that even reached the halls of Congress swept the nation. Careers and reputations were ruined. Here's a video of a news report on the Congressional hearings and court case in New York that ended these shows.
I think the scandals were the beginning of the loss of our innocence in this country.