As baseball grew in popularity in the early 20th century, Major League Baseball began instituting many changes. Some of the ones that had the most impact were baseball field changes and rule changes such as moving back the outfield walls, lowering the pitcher’s mound, banning the spitball, counting saves and creating the designated hitter.

Baseball can be divided into many different eras, depending on who is doing the division. These are some of the biggest baseball field changes and other rule changes between 1920 and 1973, the year the designated hitter changed the game.

No Spitball

Baseball banned the spitball in 1920, along with any other odd pitching deliveries. However, they had to revisit this rule 48 years later, when a rash of “moistened” balls were making their way onto the field. The spitball rule was rewritten to take these practices out of the game.

Counting RBIs

Another rule change in 1920 added runs batted in as part of the official baseball score.

Frivolous steals

Baseball officials were very busy in 1920! In that year, they also decided to stop counting steals made in the 9th inning of one-sided games. These steals often completed uncontested by the defense, are regarded as “frivolous.”

Minimum Home Run Distance

In 1925, baseball officials decided on another major baseball field change. They made the minimum home run distance at least 250 feet. In 1958, that rule changed yet again because of the Dodgers move from Brooklyn to Los Angeles. Because the Dodgers played initially at a stadium, the L.A. Memorial Coliseum, not built for baseball, the outfield wall truly was only 250 feet away and the team had to erect a 40-foot high screen to protect against short home runs. The new rule calls for at least 325 feet to the foul poles and 400 feet to centerfield. Some stadiums have been allowed to build slight smaller stadiums.

Pitcher’s Mound Height

Up until 1969, the pitcher’s mound could be 15 inches higher than home plate. However, after a 1968 season in which pitchers dominated hitters, a season called “The Year of the Pitcher,” baseball decided to lower the mound to 10 inches. The pitcher’s mound remains 60 feet, 6 inches from the back of home plate.

Saves Added

Saves did not become an official part of the statistics of the game until 1969.

Batting Helmets

It’s hard to believe it took this long, but players were not mandated to wear batting helmets by Major League Baseball until 1971.

Designated Hitter

In 1973, this rule changed the American League forever. No longer requiring pitchers to bat, the role allowed teams to insert another hitter into the lineup who didn’t have to play the field. That extended the careers of players who could no longer field a position well but could still rake at the plate. It remains one of the most controversial moves in the baseball rule change timeline, with purest saying that pitchers should have to bat.

Those are some of the biggest rule changes and baseball field changes between 1920 and 1973. They can have an impact on how you build teams from these historic eras when you play simulated and fantasy baseball.