March 6 – John Rogers and A.J. Reach, owners of the Philadelphia Phillies, are formally acquitted in court from damages from the 1903 Baker Bowl incident. Suit had originally been filed against the owners after a balcony at the stadium collapsed. The collapse left 232 fans injured, and another 12 perished.
On Opening Day, New York Giants catcher Roger Bresnahan wears shin guards for the first time in a major league game. The leg guards, usually used in cricket, come in handy, protecting Bresnahan from a fifth-inning foul tip. Other catchers will soon follow Bresnahan's lead and wear similar shin guards.
May 10 – The Chicago White Sox purchase the contract of First baseman Jake Stahl from the Washington Senators.
May 21 – The Chicago Cubs defeat the New York Giants 3–0, knocking the Giants out of first place. Giants fans begin to riot and charge the field, anger focused on umpires Hank O'Day and Bob Emslie, who are surrounded and led to safety by players for the Cubs and Giants, while Pinkerton guards fire into the air to keep the crowd at bay.
June 15 – Lave Cross is released by the Washington Senators.
June 28 – The last-place Washington Senators steal a record 13 bases off catcher Branch Rickey in a 16–5 victory over New York Highlanders. Rickey, acquired last February from the St. Louis Browns, is pressed into service despite a bad shoulder because of an injury to starting pitcher Red Kleinow. Rickey's first throw to second base ends up in right field and the subsequent tosses are not much better. He almost nips Jim Delahanty on a steal of third base. In his eight innings, relief pitcher King Brockett helps Washington with a deliberate windup. Only pitcher Long Tom Hughes and second baseman Nig Perrine are steal-less, while Hal Chase swipes one for New York.
September 8 – Future hall of fame inductee Bill McKechnie makes his major league debut, getting one hit in four at bats. It was as a manager, that McKechnie would make his mark, winning four pennants and two World Series titles.
September 20 – One week after recording a shutout in his major league debut, Pittsburgh Pirates pitcher Nick Maddox hurled a no-hitter against the Brooklyn Superbas in a 2–1 Pirates win. At the age of 20 years and ten months, Maddox becomes (and still is) the youngest pitcher to throw a no-hitter in major league history.
September 25 – Honus Wagner steals four bases, including second base, third base and home plate in the second inning against the New York Giants. Not to be outdone, his teammate Fred Clarke also swipes four bases for the only time in his career.
October 12 – In Game 5 of the World Series the Chicago Cubs would win their first World Championship by defeating the Detroit Tigers, 2–0. The Cubs would take the final four games of the series after Game 1 was declared a tie due to darkness with the score knotted at 3–3 in the 12th inning.
November 5 – The New York Highlanders purchase the contract of infielder Hobe Ferris from the Boston Americans. Ferris' stay in New York is short as just hours later, he, along with infielder Jimmy Williams, and outfielder Danny Hoffman, are traded to the St. Louis Browns in exchange for Pitcher Fred Glade, outfielder Charlie Hemphill and Outfielder/infielder Harry Niles.
January 16 – Jake Evans, 50, right fielder who played from 1879 through 1885 with four National League teams
January 19 – William A. Nimick, 58, president of the Pittsburgh Alleghenys (1885–1890) and part-owner of the team
March 12 – Pat Hynes, 23, outfielder for the St. Louis Browns/Cardinals from 1903 to 1904
March 28 – Chick Stahl, 34, outfielder for Boston teams in the NL and AL, and manager of the Red Sox since August, who batted .305 lifetime; had three triples in 1903 World Series, and led AL in triples in 1904
June 20 – Ezra Sutton, 56, third baseman for Boston who led the National League in hits in 1884, was fifth player to collect 1000 hits, and batted .300 three times in the National Association and four times in the National League
