1900s baseball seasons
120 team seasons across 9 years.
1909
- Boston Red Sox — 37 players
- Chicago Cubs — 31 players
- Chicago White Sox — 30 players
- Cincinnati Reds — 44 players
- Cleveland Naps — 37 players
- Detroit Tigers — 29 players
- New York Giants — 30 players
- New York Highlanders — 34 players
- Philadelphia Athletics — 31 players
- Philadelphia Phillies — 29 players
- Pittsburgh Pirates — 29 players
- St. Louis Browns — 32 players
- St. Louis Cardinals — 35 players
- Washington Senators — 44 players
1908
- Boston Red Sox — 41 players
- Chicago Cubs — 26 players
- Chicago White Sox — 24 players
- Cincinnati Reds — 33 players
- Cleveland Naps — 33 players
- Detroit Tigers — 24 players
- New York Giants — 30 players
- New York Highlanders — 32 players
- Philadelphia Athletics — 37 players
- Philadelphia Phillies — 27 players
- Pittsburgh Pirates — 32 players
- St. Louis Browns — 23 players
- St. Louis Cardinals — 30 players
- Washington Senators — 25 players
1907
- Boston Americans — 40 players
- Chicago Cubs — 24 players
- Chicago White Sox — 23 players
- Cincinnati Reds — 30 players
- Cleveland Naps — 26 players
- Detroit Tigers — 24 players
- New York Giants — 27 players
- New York Highlanders — 33 players
- Philadelphia Athletics — 24 players
- Philadelphia Phillies — 24 players
- Pittsburgh Pirates — 32 players
- St. Louis Browns — 25 players
- St. Louis Cardinals — 30 players
- Washington Senators — 36 players
1906
- Boston Americans — 31 players
- Chicago Cubs — 23 players
- Chicago White Sox — 25 players
- Cincinnati Reds — 35 players
- Cleveland Naps — 25 players
- Detroit Tigers — 24 players
- New York Giants — 25 players
- New York Highlanders — 26 players
- Philadelphia Athletics — 29 players
- Philadelphia Phillies — 24 players
- Pittsburgh Pirates — 32 players
- St. Louis Browns — 19 players
- St. Louis Cardinals — 41 players
- Washington Senators — 28 players
1905
- Boston Americans — 27 players
- Chicago Cubs — 20 players
- Chicago White Sox — 19 players
- Cincinnati Reds — 26 players
- Cleveland Naps — 27 players
- Detroit Tigers — 30 players
- New York Giants — 21 players
- New York Highlanders — 34 players
- Philadelphia Athletics — 19 players
- Philadelphia Phillies — 24 players
- Pittsburgh Pirates — 28 players
- St. Louis Browns — 25 players
- St. Louis Cardinals — 30 players
- Washington Senators — 27 players
1904
- Boston Americans — 18 players
- Chicago Cubs — 28 players
- Chicago White Sox — 24 players
- Cincinnati Reds — 21 players
- Cleveland Naps — 24 players
- Detroit Tigers — 25 players
- New York Giants — 23 players
- New York Highlanders — 26 players
- Philadelphia Athletics — 21 players
- Philadelphia Phillies — 31 players
- Pittsburgh Pirates — 33 players
- St. Louis Browns — 25 players
- St. Louis Cardinals — 25 players
- Washington Senators — 27 players
1903
- Boston Americans — 20 players
- Chicago Cubs — 27 players
- Cincinnati Reds — 28 players
- Cleveland Naps — 28 players
- Detroit Tigers — 26 players
- New York Giants — 20 players
- New York Highlanders — 28 players
- Philadelphia Athletics — 22 players
- Philadelphia Phillies — 24 players
- Pittsburgh Pirates — 32 players
- St. Louis Browns — 26 players
- St. Louis Cardinals — 32 players
- Washington Senators — 22 players
1902
- Boston Americans — 24 players
- Chicago White Stockings — 20 players
- Cincinnati Reds — 28 players
- Detroit Tigers — 28 players
- New York Giants — 39 players
- Philadelphia Athletics — 27 players
- Philadelphia Phillies — 33 players
- Pittsburgh Pirates — 27 players
- St. Louis Browns — 21 players
- St. Louis Cardinals — 27 players
- Washington Senators — 19 players
1901
- Baltimore Orioles — 23 players
- Boston Americans — 24 players
- Chicago White Stockings — 21 players
- Cincinnati Reds — 33 players
- Detroit Tigers — 19 players
- Milwaukee Brewers — 26 players
- New York Giants — 34 players
- Philadelphia Athletics — 31 players
- Philadelphia Phillies — 21 players
- Pittsburgh Pirates — 27 players
- St. Louis Cardinals — 25 players
- Washington Senators — 19 players