Although the Negro American League would last until 1960, 1951 was, notably, the last season in which the Negro American League was considered major-league caliber, which was itself the last major Negro league baseball organization.
May 2 – A Special Pinch Hit Home Run: The Batter, Pitcher, and Catcher Were Jewish
On May 2, 1951, at Briggs Stadium in Detroit, Philadelphia A's pinch hitter Lou Limmer stepped into the batters box to face the Tigers' Saul Rogovin. The 6'2" right-hander peered in to get the signal from catcher Joe Ginsberg, nodded assent, and went into the windup. Around came the arm, in came the pitch and Limmer swung, sending a drive to deep right that cleared the fence for a home run. Now, pinch hit home runs are not unique, but what is unique is that the pitcher, the catcher, and the hitter were all Jewish. It is the only known time in major league baseball that has occurred.
July 28 – Clyde Vollmer, who started the month on the bench, continues his explosive fireworks against the Indians. Vollmer singles in the tying run in the 15th inning and then in the 16th hits a grand slam off reliever Bob Feller for an 8-4 Red Sox win. The grand slam is the latest hit in a game in major-league history. Mickey McDermott pitches all 16 innings for the Sox, striking out 15 and walking one.
August 19 – Bill Veeck, the showman and maverick owner of the St. Louis Browns, pulls off one of the greatest stunts in baseball history. In the second game of a doubleheader against the Detroit Tigers, Veeck sends Eddie Gaedel to the plate as a pinch-hitter for leadoff batter Frank Saucier. At 3 feet 7 inches (1.09 m) tall, Gaedel became the shortest player in baseball history. Due to his extremely small strike zone, Gaedel walked on four consecutive pitches and was immediately pulled for a pinch-runner. American League president Will Harridge, saying Veeck was making a mockery of the game, voided Gaedel's contract the next day. Detroit went on to win the game, 6-2.
October 3 – The New York Giants had been thirteen and one-half games behind the National League leading Brooklyn Dodgers in August, but under Leo Durocher's guidance and with the aid of a sixteen-game winning streak, caught the Dodgers to tie for the lead with two days left in the season. As both teams won their last two games, they ended up tied. The two teams play a best-of three playoff. In Game 3 with one out in the ninth inning and runners on second and third, the Giants were down 4-2 to the Dodgers when Bobby Thomson hit a home run to win the game 5-4. The "Shot heard 'round the world" clinched the National League pennant for the Giants, and WMCA-AM radio announcer Russ Hodges' frantic "The Giants won the pennant!", said four times consecutively, is one of the most famous home run calls in baseball history.
November 10 – In Tokyo, Japan 50,000 fans are on hand as an American All-Star team battles a Central League All-Star team. Joe DiMaggio hits a 400 ft. home run in the eighth inning to tie the game at 1–1, then his younger brother Dom laces an RBI-triple in the ninth and later scores to give the Americans a 3–2 victory. The Americans have won 12 games and tied one.
March 20 – Roscoe Coughlin, 83, pitcher for two seasons in the NL, 1890–1891.
March 25 – Eddie Collins, 63, Hall of Fame second baseman and a career .333 hitter for the Athletics and White Sox, the 1914 AL MVP, the sixth player to make 3000 hits, and second to Ty Cobb in career stolen bases.
May 26 – George Winter, 73, pitcher who won 82 games for the Boston Americans/Red Sox from 1901 to 1908, and the only member both of the original 1901 and 1908 teams.
July 9 – Harry Heilmann, 56, right fielder and four-time American League batting champion who hit .342 in his career, primarily with the Detroit Tigers.
August 1 – Harry Curtis, 68, catcher for the 1907 New York Giants.
August 2 – Guy Cooper, 68, pitcher for the New York Yankees and Boston Red Sox in the 1910s.
August 4 – Tony Tonneman, 69, catcher who played briefly for the 1911 Boston Red Sox.
August 10 – Win Kellum, 75, who in 1901 became the first Opening Day starting pitcher in Boston American League franchise's history.
September 16 – Bill Klem, 77, named "father of baseball umpires", who worked in a record 18 World Series during a 37-year career, and introduced the inside chest protector.
October 27 – John Brock, 55, backup catcher for the St. Louis Cardinals in the 1917 and 1918 seasons.
November 18 – Wally Mayer, 61, catcher who played from 1911 through 1919 for the Chicago White Sox, Boston Red Sox and St. Louis Browns.
November 19 – Marty Griffin, 50, pitcher for the 1928 Boston Red Sox.
November 26 – Pete Hill, 71, baseball's first great African American outfielder.
December 5 – Shoeless Joe Jackson, 63, a career .356 hitter who was the most prominent of the eight players banned from baseball after the Black Sox scandal. He is the first of those eight to die.
December 8 – Bobby Lowe, 86, second baseman for multiple Boston champions in the 1890s.