April 29 – In the seventh game of the season, New York Yankeescenter fielder Joe DiMaggio makes a sharp turn while fielding a liner facing the Washington Senators and tears muscles in his right foot. The Yankees lose the game and DiMaggio will miss the next 35 games.
April 30 – Lou Gehrig goes hitless in four at-bats against the Washington Senators and is now hitting just .143 this season. He had just played his 2,130th consecutive major league game. No one knew it would be the very last of his career.
May 2 – New York Yankees first baseman Lou Gehrig voluntarily benches himself "for the good of the team" ending his consecutive-game streak at 2,130. Babe Dahlgren replaces him in the line-up, and goes two-for-five with a home run. The Yankees beat the Detroit Tigers 22–2 behind Red Ruffing.
June 4 – The St. Louis Browns sweep a double header from the Washington Senators to end an eleven-game losing streak. The Browns then go on to lose their next six in a row. The Browns never won more than two games in a row all season.
June 5 – Detroit Tigers pitcher Tommy Bridges holds the New York Yankees to just four hits as the Yankees are shut out for the only time all season, 3–0.
June 28 – The New York Yankees defeat the Philadelphia Athletics 23–2 & 10–0 in a double header. In the first game, the Yankees hit eight home runs, and followed that with five more in the second. Both totals set a Major League record for most home runs in a game as well as their total of fifty-three total bases in a doubleheader.
July 3 – In the St. Louis Cardinals' 5–3 victory over the Chicago Cubs, Johnny Mize goes four-for-four, equaling a National League record four extra-base hits, including a double, triple and two home runs.
July 4 – Lou Gehrigappreciation day is celebrated at Yankee Stadium. Numerous people, including many from other major league teams, came forward to give Gehrig gifts and to shower praise on the dying slugger. The Yankees retired his uniform number (4), becoming the first player in major league history to be afforded that honor. Babe Ruth even showed up and ended their long-standing feud by giving his old teammate a hug. After the presentations, Gehrig approached the microphone, and addressed the crowd:
Fans, for the past two weeks you have been reading about the bad break I got. Yet today I consider myself the luckiest man on the face of this earth. I have been in ballparks for seventeen years and have never received anything but kindness and encouragement from you fans. Look at these grand men. Which of you wouldn't consider it the highlight of his career just to associate with them for even one day? Sure, I'm lucky. Who wouldn't consider it an honor to have known Jacob Ruppert? Also, the builder of baseball's greatest empire, Ed Barrow? To have spent six years with that wonderful little fellow, Miller Huggins? Then to have spent the next nine years with that outstanding leader, that smart student of psychology, the best manager in baseball today, Joe McCarthy? Sure, I'm lucky. When the New York Giants, a team you would give your right arm to beat, and vice versa, sends you a gift – that's something. When everybody down to the groundskeepers and those boys in white coats remember you with trophies – that's something. When you have a wonderful mother-in-law who takes sides with you in squabbles with her own daughter – that's something. When you have a father and a mother who work all their lives so you can have an education and build your body – it's a blessing. When you have a wife who has been a tower of strength and shown more courage than you dreamed existed – that's the finest I know. So I close in saying that I may have had a tough break, but I have an awful lot to live for.
July 8 – The Washington Senators' Mickey Vernon makes his major league debut as a pinch runner in the first game of a double header with the Philadelphia A's. He does not log an at-bat, however, he goes one-for-five in the second game and scores a run.
July 9 – The Philadelphia Phillies defeat the Boston Bees, 3–1, to snap an eleven-game losing streak.
August 5 – The New York Yankees trade Vince DiMaggio to the Cincinnati Reds.
August 6 – Already behind 10–1 to the Detroit Tigers, Boston Red Sox manager Joe Cronin sends Jimmie Foxx to the mound to pitch the ninth inning. He records a perfect 1–2–3 inning.
Red Rolfe of the New York Yankees started a streak of 18 consecutive games in which he scored at least one run. During those games, he scored a total of 30 runs.
With a 5–3 victory over the Pittsburgh Pirates, the St. Louis Cardinals complete a ten-game winning streak. They are still, however, eight games back of the first place Cincinnati Reds. The Reds snap the streak on August 12, however, the Cards take two of their three meetings at Sportsman's Park to move within 6.5 of first place.
August 20 – The Pittsburgh Pirates and Chicago Cubs split a double header at Forbes Field. The victory in the second game snaps a twelve-game losing streak for the Bucs.
August 26 – The double header between the Brooklyn Dodgers and Cincinnati Reds at Ebbets Field is telecast on Channel W2XBS in Brooklyn.
September 13 – Early Wynn loses his major league debut, 4–2 to the Chicago White Sox.
September 18 – The St. Louis Browns lose their 100th game of the season, 6–2 to the New York Yankees.
September 19 – The New York Yankees defeat the Chicago White Sox, 6–2, for their 100th victory of the season.
September 23 – The Brooklyn Dodgers defeat the Philadelphia Phillies 22–4. The Dodgers go on to sweep the Phillies in the four game set at Shibe Park, handing them losses number 100 & 101 on the 24th.
September 29 – The second game of the double header between the Cleveland Indians and Detroit Tigers at Briggs Stadium is called after five innings due to rain. Hal Newhouser pitches all five innings for Detroit, and is the losing pitcher in his major league debut.
September 30 – In the second game of a double header with the Chicago Cubs, St. Louis Cardinals pitcher Murry Dickson makes his major league debut. He pitches 3.2 without giving up a run, and strikes out in his only at-bat.
October 4 – Bill Dickey's single in the bottom of the ninth wins game one of the 1939 World Series for the New York Yankees, 2–1. This is the first World Series appearance for the Cincinnati Reds in 20 years.
October 5 – Monte Pearson holds the Cincinnati Reds to just two hits, as the Yankees take game two of the World Series, 4–0.
October 7 – The Reds take a 3–2 lead in the second inning only to have Joe DiMaggio hit a two run home run in the top of the third to put the Yankees on top for good on their way to a 7–3 victory.
October 8 – An error by Billy Myers allows the Yankees to tie it in the ninth. Then, costly errors in the tenth inning by Myers, Ival Goodman and Bucky Walters lead to three runs as the New York Yankees defeat the Cincinnati Reds, 7–4, in Game Four of the World Series to win a record fourth consecutive World Championship, and eighth overall, four games to none.
Pitcher Victor Starffin wins his 42nd game in a 96-game season of the Japanese Professional Baseball League, leading the Yomiuri Giants to the Championship title, while setting a post-1900 World Record for season victories that will be equaled by Kazuhisa Inao in 1961 but never broken. Starffin will follow his record performance with another 38 wins in 1940. Born in Russia, he moved to Asahikawa, Hokkaidō at a young age, and was selected as part of the national baseball team for an exhibition game against the United States in 1934. From 1936 through 1955 Starffin won 303 games, to become the first pitcher in Japanese baseball history to reach 300 victories.
December 6 – In a trade of veteran shortstops, or "worn-out shortstops", as one newspaper described it, the Chicago Cubs acquire Billy Rogell from the Detroit Tigers for Dick Bartell. Rogell, who injured his arm playing handball the previous year, hits just .136 before hanging up his spikes. The Tigers will release "Rowdy Richard" five games into the 1941 season, but he will stick with the New York Giants until 1946.
December 9 – The Detroit Tigers trade Benny McCoy and George Coffman to the Philadelphia A's for Wally Moses. The trade is voided by Commissioner Kenesaw Mountain Landis, and the players return to their original teams on January 14, 1940. The commissioner declared McCoy a free agent because he had been "hidden" from other teams. Judge Landis declares 87 more Tigers farmhands free agents due to their concealment in the minor leagues.
January 7 – Bert Weeden, 56, pinch-hitter for the 1911 Boston Rustlers and also a catcher/manager in the minors during 17 seasons spanning 1903–1923.
January 9 – Louis Pelouze, 75, outfielder for the St. Louis Maroons in the 1886 season.
January 13 – Jacob Ruppert, 71, New York Yankees owner since 1914.
January 18 – Cliff Heathcote, 40, outfielder who hit .275 with 42 home runs and 448 RBI for the St. Louis Cardinals, Chicago Cubs, Cincinnati Reds and Philadelphia Phillies over 15 seasons from 1918–1932, and a member of the Cubs club that won the National League pennant in 1929.
January 25 – Abner Dalrymple, 81, outfielder who played from 1878 through 1891 for the Milwaukee Grays, Chicago White Stockings, Pittsburgh Alleghenys, and Milwaukee Brewers, and also a prolific hitter who, at the time of his retirement, had collected several titles in batting average, home runs, hits, and runs scored.
January 28 – Bill Cristall, 63, Ukrainian born pitcher who played briefly for the Cleveland Blues in 1901.
March 2 – Alex McFarlan, 59, outfielder for the 1892 Louisville Colonels.
March 8 – Scott Stratton, 69, pitcher for three teams from 1888 to 1895, primarily with the Louisville Colonels, who posted 34 wins in 1890 which included 15 straight victories, while leading the American Association in winning percentage and ERA in the same season.
March 15 – Cal Broughton, 78, catcher who played for six different American Association and National League teams in part of four seasons spanning 1883–1888.
March 16 – Sam Dungan, 72, right fielder who hit .301 for three teams in a span of five seasons from 1892–1901, while posting a very solid 3.14 walk-to-strikeout ratio (116-to-37) in 382 games.
March 17 – William Burke, 73, pitcher/outfielder for the 1887 Detroit Wolverines of the National League.
March 18 – Ralph Miller, 43, third baseman who played from 1920 to 1921 with the Philadelphia Phillies and for the Washington Senators in 1924.
March 25 – Tiny Chaplin, 33, pitcher who played for the New York Giants and the Boston Bees in three seasons between 1928 and 1936.
March 28 – Fred Goldsmith, 82, pitcher for four different teams between 1875 and 1884, who steadfastly claimed that he had first thrown the curveball in 1870, six years earlier than Candy Cummings, who gained credit for the development of the pitch.
June 6 – Simmy Murch, infielder who played for the St. Louis Cardinals and Brooklyn Superbas in part of three seasons spanning 1904–1908.
June 8 – Pat Paige, 57, pitcher for the Cleveland Naps during the 1911 season.
June 11 – John Henry, 75, outfielder/pitcher for the Cleveland Blues, Baltimore Orioles, Washington Nationals and New York Giants in a span of four seasons from 1884–1890.
June 17 – Allen Sothoron, 46, spitball pitcher and a master of trick deliveries between the 1914 and 1926 seasons, who spent most of his career with the St. Louis Browns and the St. Louis Cardinals, and later coached and managed in the minors from 1928 to 1938.
June 18 – Murphy Currie, 45, pitcher for the St. Louis Cardinals in 1916.
June 25 – Heinie Smith, 67, second baseman for the Louisville Colonels, Pittsburgh Pirates, New York Giants and Detroit Tigers between 1897 and 1903, who also managed the Giants in the 1902 season.
July 7 – Deacon White, 91; Hall of Fame catcher and third baseman who, despite playing without a glove, mask, chest protector and shin guards, caught more games (409) than any catcher during the 1870s and later became a member of the legendary Big Four infield with Dan Brouthers (1B), Hardy Richardson (2B) and Jack Rowe (SS), while being one of the game's most feared hitters – winning two batting titles (1875; 1877) and three RBI crowns (1873; 1876–1877) – as well as a major figure on five consecutive championship teams from 1873 through 1877.
July 15 – Ed Biecher, 63, outfielder who played from 1897 to 1898 with the St. Louis Browns and Cleveland Spiders, and remained active as a player/manager in the Minor Leagues through 1903.
July 20 – Jack Reis, 48, pitcher who played briefly for the St. Louis Cardinals in the 1911 season.
July 26 – Peaches Graham, 62, catcher who played for the Cleveland Bronchos, Chicago Cubs, Boston Doves/Rustlers and Philadelphia Phillies over seven seasons spanning 1902–1912.
July 29 – John Sowders, 72, pitcher who played with the Indianapolis Hoosiers in 1887 and for the Kansas City Cowboys and Brooklyn Ward's Wonders from 1889 to 1890.
September 17 – Tom Hart, 70, catcher/outfielder for the 1891 Washington Statesmen.
September 18 – Toots Coyne, 44, third baseman who played for the Philadelphia Athletics during the 1914 season.
September 25 – Frank LaPorte, 59, infielder who posted four .300 seasons in an eleven-year career, led the Federal League for the most RBI in 1914, and was the first man to play both for the New York Yankees and Boston Red Sox intense rivals.
September 27 – Sweetbread Bailey, 44, pitcher who played from 1919 through 1921 for the Chicago Cubs and Brooklyn Robins, and also served in the military during World War I conflict.
October 9 – Biff Schaller, 50, outfielder who played with the Detroit Tigers in 1911 and the Chicago White Sox in 1913.
October 16 – Nick Allen, 51, catcher for the Buffalo Buffeds, Chicago Cubs and Cincinnati Reds in a span of six seasons from 1914–1920, who later played and managed in the minor leagues through 1936 and earned the nickname "Roarin' Nick" for his notorious altercations with umpires.
October 17 – George Bristow, 69, outfielder for the 1899 Cleveland Spiders and later a long time player and manager in the minor leagues.
October 19 – Red Downs, 56, second baseman for the Detroit Tigers, Brooklyn Dodgers and Chicago Cubs from 1907 through 1912, and also a member of the Tigers club that won the American League pennant in 1908, who gained notoriety later as an armed robber during the Great Depression.
October 22 – Dale Williams, 84, pitcher for the Cincinnati Reds in the 1876 season.
October 26 – Ed Lennox, 55, third baseman who played for the Philadelphia Athletics, Brooklyn Superbas, Chicago Cubs and Pittsburgh Rebels in parts of six seasons spanning 1906–1915.
December 3 – Frank Killen, 69, pitcher for the Milwaukee Brewers, Washington Senators, Pittsburgh Pirates, Boston Beaneaters and Chicago Orphans, who won 164 games from 1891–1900, including two 30-win seasons and two 20-win seasons.
December 11 – Dallas Bradshaw, 44, second baseman who played briefly for the Philadelphia Athletics in the 1917 season.
December 18 – Heywood Broun, 51, sportswriter and editor in New York City since the early 1910s.
December 26 – Clyde Engle, 55, valuable utility at all positions except pitcher and catcher for four teams from 1909 through 1916, who scored the tying run for the Boston Red Sox in the 10th inning of final Game 8 of the 1912 World Series after his earlier pop fly had been dropped, preserving the victory for the eventual champions Red Sox.