1988: Major League Baseball begins tracking pitch counts as an official statistic.
1989: Then-23-year-old Al Leiter of the New York Mets throws 163 pitches in his second start of the year. Starting pitchers throw at least 140 pitches in 55 games this season.
1990: Knuckleball specialist Tim Wakefield, then of the Pittsburgh Pirates, throws 172 pitches against the Atlanta Braves.
1998: Baseball Prospectus writer Rany Jazayerli introduces the “Pitcher Abuse Points” statistic, the first attempt to quantify the damage inflicted on a pitcher’s health in a given game.
1999: Chicago Cubs pitching prodigy Kerry Wood tears his ulnar collateral ligament and misses the entire year, after a rookie season in which he shouldered a heavy pitching load at age 21.
June 1999: Dr. James Andrews, an influential and world-renowned American orthopedic surgeon, suggests 100 pitches as a ballpark figure for when an arm tires during a pitching outing.
2004: Jazayerli amends the Pitcher Abuse Points statistic to consider new research on pitcher arm injuries.
2008: Vermont becomes the first state to spurn an innings limit in high school games in favor of a hard pitch-count limit.
2010: Little League adopts pitch-count rules based on a player’s age.
2010: The Yankees and Red Sox local baseball broadcasting channels become the first to display pitch counts on-screen during games.
September 2012: The Washington Nationals, despite being headed for a playoff appearance, shut down all-star starting pitcher Stephen Strasburg after he reaches his innings limit for the year. Strasburg tore his UCL two years earlier, at 21, during his rookie season.
2014: ESPN begins displaying pitch counts on-screen during games.
2015: The National Federation of State High School Associations (NFHS) holds a joint meeting with the Sports Medicine Advisory Committee and USA Baseball’s medical safety committee to discuss pitch-count limits for youths.
April 2016: Ross Stripling of the Los Angeles Dodgers is pulled from his Major League debut after reaching 100 pitches, despite throwing a no-hitter through 7 1/3 innings.
April 2016: High school senior and Illinois State University commit Brady Huffman throws 167 pitches in a 10-inning game, drawing national attention and criticism of his high school coach, Roger Butler.
July 2016: NFHS mandates that each state in which baseball is sanctioned must enact a pitch-count rule.
September 2016: Idaho High School Activities Association approves a draft of pitch restrictions.
December 2016: The Idaho association finalizes adoption of current pitch-count restrictions.