National League / Major League Rule Change Timeline In Chronological Order
Year	Change In Official Major League Rules
1877	Canvas bases 15 inches square were introduced.
	Home plate was placed in the angle formed by the intersection of the first and third base lines.
	The hitter was exempted from a time at bat if he walked.
1879	Player reserve clause was for the first time put into a contract.
	The number of "called balls" became 9 and all balls were either strikes, balls or fouls.
	The pitcher had to face a batsman before pitching to him.
	A staff of umpires was first introduced.
1880	Base on balls was reduced to 8 "called balls."
	The base runner was out if hit by a batted ball.
	The catcher had to catch the pitch on the fly in order to register an out on a third strike.
1883	The "foul bound catch" was abolished and the pitcher could deliver a ball from above his waist.
1884	All restrictions on the delivery of a pitcher were removed.
	Six "called balls" became a base on balls.
	Championships were to be decided on a percentage basis.
1885	One portion of the bat could be flat (one side).
	Home base could be made of marble or whitened rubber.
	Chest protectors worn by catchers and umpires came into use.
1887	The pitcher's box was reduced to 4 feet by 5 1/2 feet.
	Calling for high and low pitches was abolished.
	Five balls became a base on balls.
	Four "called strikes" were adopted for this season only.
	Bases on balls were recorded as hits for this season only.
	The batter was awarded first base when hit by a pitch.
	Home plate was to be made of rubber only - dropping the marble type and was to be 12 inches square.
	Coaches were recognized by the rules for the first time ever.
1888	Player reserve clause was written into the contracts of minor leaguers for the first time.
	The base on balls exemption from a time at bat was restored.
	A batsman was credited with a base hit when a runner was hit by his batted ball.
1889	Four balls became a base on balls.
	A sacrifice bunt was statistically recognized.
1891	Substitutions were permitted at any point in the game.
	Large padded mitts were allowed for catchers.
1893	Pitching distance increased from 50 feet to 60 feet 6 inches.
	The pitching box was eliminated and a rubber slab 12 inches by 4 inches was substituted.
	The pitcher was required to place his rear foot against the slab.
	The rule exempting a batter from a time at bat on a sacrifice was instituted.
	The rule allowing a flat side to a bat was rescinded and the requirement that the bat be round and wholly of hard wood was substituted.
1894	Foul bunts were classified as strikes.
1895	Pitching slab was enlarged to 24 inches by 6 inches.
	Bats were permitted to be 2 3/4 inches in diameter and not to exceed 42 inches.
	Infield-fly rule was adopted.
	A held foul tip was classified as a strike.
1901	Catchers were compelled to remain continuously under the bat.
1903	Foul strike rule was adopted by the American League.
1904	Height of the mound was limited to 15 inches higher than the level of the baselines.
1908	Pitchers were prohibited from soiling a new ball.
	Shinguards were reintroduced.
	The sacrifice fly rule was adopted.
1910	The cork center was added to the official baseball.
1917	Earned-run statistics and definitions were added to the rules.
1920	All freak deliveries, including the spitball, were outlawed.
	The failure of a preceding runner to touch a base would not affect the status of a succeeding runner.
	The batter was given credit for a home run in the last of the ninth inning if the winning run was on base when the ball was hit out of the field.
	The number of runs batted in were to be included in the official score.
	Frivolous ninth-inning uncontested steals in one-sided games were discarded.
1925	Pitcher was allowed to use a resin bag.
	The minimum home-run distance was set at 250 feet.
1931	Sacrifice fly rule was brought back, this time with a man scoring after the catch only.
	Defensive interference was changed from an offense solely by a catcher to one by a fielder as well.
	No fielder could take a position in line with a batter's vision with the deliberate intent to in any way distract the batter.
	Regulations referring to a batter contacting his own ball were clarified as was the area of bases awarded a batter when a defensive player threw his glove at a batted or thrown ball or in the case of spectator interference.
1953	Players were to remove their gloves from the field (in 1954) when batting and no equipment was to show on the field at any time.
1959	Regulations were set up for minimum boundaries for all new parks, 325-400-325 feet.
1968	The anti-spitball rule was rewritten and tightened up because of the wave of moistened pitches that floated plateward the prior season.
1969	The pitcher's mound was dropped five inches.
	The strike zone was shrunken to the area from the armpits to the top of the batter's knees.
	The save rule was added to the official rules for the first time.
1971	All major-league players were ordered to wear protective helmets.
1973	The rule on glove size and color was minutely outlined for standardization.
	The American League began using designated hitter for pitchers on an experimental basis.
1974	The save rule was rewritten.
	Minimum standards for individual championships were outlined.
1975	The ball was permitted to be covered with cowhide because of the shortage of horses.
	Suspension for three days became mandatory if batter were to hit a fair ball with a filled, doctored or flat-surfaced bat.
	The save rule was changed again.
2008	MLB adds limited (home run calls, fair or foul) instant reply to be in effect for all games starting on Friday, August 29th.
2016	Slides on potential double plays will require that base runners must make a bona fide attempt to reach and remain on base. [Press Release: ]
Year	Change In Official Major League Rules
Major League Baseball Rules Timeline by Baseball Almanac

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