Direct answer: Major League Baseball used a 154-game schedule from the early 1900s (after the modern two‑league era began) until the early 1960s, when it expanded to a 162-game schedule following league expansion in 1961–1962.

Historical context

  • The 154-game schedule became the standard for both the National and American Leagues in the early 20th century and remained the traditional full season length for many decades.
  • When MLB expanded by adding teams (the American League added two teams in 1961 and the National League did likewise in 1962), the leagues lengthened the schedule to 162 games to keep a balanced number of home and away dates; that change effectively ended the long run of 154-game seasons.

Why the change happened

  • With more teams and the desire for balanced pairings (an even number of opponents and a symmetric home/away split), MLB extended the season by eight games per team so each club would still play a similar number of games against each opponent.

Brief timeline (illustrative)

  • Early 1900s: 154 games becomes the standard schedule.
  • 1961–1962: Schedule expands to 162 games concurrent with league expansion.

Short example

  • Before expansion: an 8‑team league could easily structure a 154‑game slate with repeated matchups; after expansion to 10 (and later more) teams, MLB added games so the schedule stayed balanced across more opponents.

Bottom note
Information gathered from public forums or data available on the internet and portrayed here.