Who knows whether it was because of the success Reggie had on the field, the attention he got for chewing sunflower seeds off of it, an increased awareness of the dangers of tobacco use, or simply the satisfaction one gets from removing the nutritious kernel from its salty hull, but players started following Jackson’s lead. Which was much to the chagrin of Major League grounds crews, who found the discarded shells difficult to clean up. By 1980, then–St. Louis Cardinals pitching coach Claude Osteen was calling it “the era of birdseed.”
In January 2004, Major League Baseball announced a new drug policy which originally included random, offseason testing and 10-day suspensions for first-time offenders, 30-days for second-time offenders, 60-days for third-time offenders, and one year for fourth-time offenders, all without pay, in an effort to curtail performance-enhancing drug use (PED) in professional baseball. This policy strengthened baseball's pre-existing ban on controlled substances , including steroids, which has been in effect since 1991.  The policy was to be reviewed in 2008, but under pressure from the . Congress , on November 15, 2005, players and owners agreed to tougher penalties; a 50-game suspension for a first offense, a 100-game suspension for a second, and a lifetime ban for a third.
Compared with the present, professional baseball in the early 20th century was lower-scoring, and pitchers, including stars Walter Johnson and Christy Mathewson , were more dominant. The " inside game ", which demanded that players "scratch for runs", was played much more aggressively than it is today: the brilliant and often violent Ty Cobb epitomized this style.  The so-called dead-ball era ended in the early 1920s with several changes in rule and circumstance that were advantageous to hitters. Strict new regulations governing the ball's size, shape and composition, along with a new rule officially banning the spitball and other pitches that depended on the ball being treated or roughed-up with foreign substances, followed the death of Ray Chapman after a pitch struck him in the head in August 1920. Coupled with superior materials available after World War I, this resulted in a ball that traveled farther when hit. The construction of additional seating to accommodate the rising popularity of the game often had the effect of reducing the distance to the outfield fences, making home runs more common.  The rise of the legendary player Babe Ruth , the first great power hitter of the new era, helped permanently alter the nature of the game. The club with which Ruth set most of his slugging records, the New York Yankees , built a reputation as the majors' premier team.  In the late 1920s and early 1930s, St. Louis Cardinals general manager Branch Rickey invested in several minor league clubs and developed the first modern " farm system ".  A new Negro National League was organized in 1933; four years later, it was joined by the Negro American League . The first elections to the National Baseball Hall of Fame took place in 1936. In 1939 Little League Baseball was founded in Pennsylvania. By the late 1940s, it was the organizing body for children's baseball leagues across the United States.