Top Viewership of All Time

Wiki

US Top 10 Network Primetime Telecasts of All Time
1. CBS 2/28/83: M*A*S*H series finale "Goodbye, Farewell & Amen" - 105.9 million viewers.
2. FOX 2/3/08: Super Bowl XLII (Giants-Patriots) - 97.5 million viewers.
3. CBS 2/21/80: Dallas episode "Who Done It?" (Who Shot J.R.?)
4. ABC 1/30/77: Roots Part VIII Finale
5. CBS 1/24/82: Super Bowl XVI (49ers-Bengals)
6. NBC 1/30/83: Super Bowl XVII (Redskins-Dolphins)
7. CBS 2/23/94: XVII Winter Olympics Ladies' figure skating (Kerrigan & Harding)
8. NBC 1/26/86: Super Bowl XX (Bears-Patriots)
9. NBC 11/7/76: Gone with the Wind
10. CBS 1/15/78: Super Bowl XII (Cowboys-Broncos)

Skipping Super Bowls & Roots episodes -
here are some others to note within the top 25;
12. NBC 1/15/70: Bob Hope Christmas Special
17. ABC 11/20/83: The Day After
19. ABC 8/29/67: The Fugitive series finale "The Judgement Part 2"
23. NBC 5/20/93: Cheers series finale "One For The Road" - 80.4 million viewers.

Other Most-Watched US Series Finales
NBC 5/14/98: Seinfeld - 76.3 million viewers.
NBC 5/6/04: Friends - 52.5 million viewers.
CBS 5/1/88: Magnum PI - 50.7 million viewers.
NBC 5/22/92: The Tonight Show Starring Johnny Carson - 50.0 million viewers.
NBC 4/30/92: The Cosby Show - 44.4 million viewers.
ABC 5/25/99: Home Improvement - 35.5 million viewers.
CBS 5/16/05: Everybody Loves Raymond - 32.9 million viewers.
NBC 5/7/92: Golden Girls - 27.2 million viewers.
NBC 5/13/04: Frasier - 25.2 million viewers.