When did each decade of sportscasting on American TV culturally begin & end

[TMC]

At least in my humble opinion.

1950s:

• Starting point (earliest): September 30, 1947 - The World Series is televised for the very first time.
  
• Starting point (latest): December 23, 1951 - The DuMont network televises its first ever live, coast-to-coast NFL broadcast, which is the NFL Championship Game between the Los Angeles Rams and Cleveland Browns.
  
• Ending point (earliest): September 30, 1961 - The Sports Broadcasting Act of 1961 is signed into law.
  
• Ending point (latest): April 17, 1965 - Major League Baseball games begin airing on ABC, marking the first time that a television network provided nationwide baseball coverage. Every team in Major League Baseball were covered with the exception of the New York Yankees and Philadelphia Phillies.

1960s:

• Starting point (earliest): December 28, 1958 - The NFL Championship Game between the Baltimore Colts and New York Giants, dubbed "The Greatest Game Ever Played" is broadcast on NBC.
  
• Starting point (latest): April 29, 1961 - The very first edition of ABC's Wide World of Sports is broadcast.
  
• Ending point (earliest): January 15, 1967 - The first ever Super Bowl is simulcast on CBS and NBC.
  
• Ending point (latest): October 13, 1971 - Game 4 of the World Series is broadcast on NBC, becoming the first ever night game in World Series history.

1970s:

• Starting point (earliest): September 21, 1970 - The very first edition of Monday Night Football airs on ABC.
  
• Starting point (latest): October 21, 1975 - Game 6 of the 1975 World Series is broadcast on NBC, which inadvertently helped changed the way that live sporting events would be televised with the creation of the "reaction shot" following Carlton Fisk's dramatic, walk-off home run in the bottom of the 12th inning.
  
• Ending point (earliest): May 14, 1981 - Game 6 of the NBA Finals is broadcast on CBS via tape delay to most of the nation. This is the final time that CBS would televise an NBA Finals game on tape delay. However, CBS would continue to air NBA playoff games on tape delay at least once a season through 1988.
  
• Ending point (latest): December 16, 1983 - Howard Cosell broadcasts his final NFL game on ABC, which was a contest between the New York Jets and Miami Dolphins. Shortly thereafter, his career you could say, really began to decline. This culminated in ABC removing him from his scheduled broadcasting duties at the 1985 World Series and replaced by Tim McCarver due to the controversy stemming from Cosell's book I Never Played the Game.

1980s:

• Starting point (earliest): September 7, 1979 - ESPN first goes on the air.
  
• Starting point (latest): January 20, 1985 - Super Bowl XIX is broadcast on ABC, becoming the very first Super Bowl to be televised by the network. Previously, the Super Bowl alternated only between CBS and NBC.
  
• Ending point (earliest): October 28, 1989 - The fourth and decisive game of the World Series airs on ABC, thus officially marking an end of ABC and NBC's network televised run with Major League Baseball that begin in 1976 for ABC and 1947 for NBC. CBS would assume the role of MLB's network television carrier beginning in 1990.
  
• Ending point (latest): January 23, 1994 - CBS airs its final NFL telecast for the time being, which was the NFC Championship Game between the Dallas Cowboys and San Francisco 49ers. CBS, who had televised NFL games since 1956, was outbid for the National Football Conference rights by the upstart Fox network.

1990s:

• Starting point (earliest): November 3, 1990 - The NBA on NBC makes its debut, replacing The NBA on CBS.
  
• Starting point (latest): August 12, 1994 - The NFL on Fox makes its debut telecast, replacing long time National Football Conference rights holder, CBS.
  
• Ending point (earliest): June 12, 2002 - NBC airs its final NBA broadcast, Game 4 of the NBA Finals. ABC would take over the NBA's network broadcast television rights going forward.
  
• Ending point (latest): February 5, 2006 - Super Bowl XL is broadcast, officially marking the end of ABC's continuous run with the NFL, which began with the launch of Monday Night Football in 1970. ESPN would assume the role of carrying MNF going forward. And come the fall of 2006, all live sporting events to air on ABC would carry the full on-air ESPN branding and presentation.

2000s:

• Starting point (earliest): September 6, 1998 - After an over four year hiatus, CBS resumes broadcasting NFL games after obtaining the American Football League rights from NBC.
  
• Starting point (latest): February 18, 2001: Fox's airs its inaugural NASCAR telecast, the Daytona 500. This represented a new era as now, NASCAR would centralize television deals instead of on an inconsistent, race by race basis.
  
• Ending point (earliest): February 1, 2009 - NBC broadcast Super Bowl XLIII. This is the first time that NBC aired a Super Bowl since Super Bowl XXXII on January 25, 1998. More significantly, this was the final NFL game to be called by John Madden.
  
• Ending point (latest): September 8, 2014 - CBS broadcasts the U.S. Open tennis tournament for the final time, after carrying the event since 1968.

2010s:

• Starting point (earliest): August 6, 2006 - Sunday Night Football on NBC debuts with the Pro Football Hall of Fame Game.
  
• Starting point (latest): August 17, 2013 - FS1, a 24 hour cable channel from Fox Sports officially launches.
  
• Ending point (earliest): June 9, 2018 - Bob Costas makes what turns out to be his final on-air assignment for NBC Sports, hosting the Belmont Stakes.
  
• Ending point (latest): February 13, 2022 - Al Michaels calls his final NFL game as NBC's lead NFL play-by-play announcer, Super Bowl LVI and his 11th and presumptuously, final Super Bowl broadcast in total. After this season, Mike Tirico would officially succeed him as the lead play-by-play announcer on NBC's Sunday Night Football telecasts.