• 1900
  Cincinnati trades young pitcher Christy Mathewson to the New York Giants for fading P Amos Rusie.
  Willie Keeler achieves his seventh consecutive 200-hit campaign. His National League-leading 204 hits come in just 136 games.
  Pittsburgh leads the league in triples with 100.
  Charlie "Piano Legs" Hickman of the last-place Giants commits a record 86 errors in his only season playing third base.
  
• 1901
  The American League begins play with eight teams. The new league directly competes with the old league in three cities: Boston, Chicago, and Philadelphia. More than 100 players from the National League jump to the new league for increased salaries, including John McGraw, Cy Young, Clark Griffith, Hugh Duffy, and Jimmy Collins.
  For the first time in the National League, foul balls are counted as strikes (before the count reaches two strikes). So total runs dropped by almost 800. The league batting average falls from .279 to .267. Even stolen bases are affected as at-bats are shortened and strikeout totals skyrocket.
• 1902
  In April, American League umpire Jack Sheridan watches as Boston's Bill Dinneen hits John McGraw of the Baltimore Orioles five times with pitches. Each time, Sheridan refuses to award McGraw first base on the grounds that McGraw got hit intentionally. Finally, Sheridan ejects McGraw. American League president Ban Johnson, McGraw's mortal enemy, backs Sheridan and suspends McGraw for five days.
  McGraw gets even with Johnson later in the year. Mugsy enlists two NL owners to secretly buy up a controlling interest in the Orioles and then release virtually the entire lineup to the New York Giants and Cincinnati Reds. Shortly afterward, McGraw is named the Giants' manager.
  Jack Chesbro of the Pittsburgh Pirates sets a record with 41 consecutive scoreless innings.
  Cleveland establishes a dubious AL record with six errors in an inning on June 2.
• 1903
  An irate Ban Johnson takes control of the Baltimore franchise and transfers it to New York to compete directly with the Giants. The AL franchise is called the "Highlanders" until 1913 when they become the "Yankees."
  Washington's star player Ed Delahanty falls from a railway trestle to his death.
  Cleveland SS John Gochnauer makes a 20th-century record 98 errors and hits .185.
  When part of Baker Bowl, the Phillies' park, collapses, 12 fans are killed.
  The Pirates pitch a record 57 consecutive scoreless innings on their way to the NL pennant.
  The Boston Americans win the first World's Series in eight games over the Pirates.
  
• 1904
  The dead-ball era begins in earnest. Cleveland is the only American League team to average four runs a game.
  Jack Chesbro of the New York Highlanders wins a record 41 games in 51 starts with 48 complete games. However, his wild pitch allows the winning run to score in a game with Boston on the final day of the season to clinch the American League pennant for the Beantowners.
  In the National League, the New York Giants clinch the crown after only 137 games of the 154-game season.
  However, owner John Brush and manager John McGraw issue a press release that calls the AL a "minor league" and states that the Giants "desire no greater glory than to win the pennant in the National League." So the Giants will not play the American League champions in the second World Series.
  After the season, owners from both leagues meet to draft a set of guidelines that establish a World Series that would never be canceled again.
  
• 1905
  The dead ball era at its worst. Only three men bat over .300 in the American League. Elmer Flick wins the title by hitting only .308, the lowest average ever to lead either major league.
  Every team has an ERA under 3.00.
  Southpaw Rube Waddell leads the AL in both wins (27) and ERA (1.48).
  The Giants take over first place in the NL on April 23 and never relinquish it the rest of the season.
  The World Series becomes the best-pitched Series ever. All five games between the Giants and the Philadelphia Athletics are shutouts. The loser, Philadelphia, has an ERA of 1.47. The Giants win behind Christy Mathewson's three shutouts. New York's ERA for the Series is a perfect 0.00.
  Waddell misses the Series because he is injured at the end of the season in a bit of horseplay with a teammate.
• 1906
  The Cubs win the NL pennant with a record 116 wins. The White Sox cop the AL flag despite a .230 team batting average. The "Hitless Wonders" Sox pull a major upset by winning the World Series.
  George Stone of the St. Louis Browns leads the AL in BA (.358), SA (.501), and total bases (291).
  The Boston Braves finish last, a record 66 1/2 games out of first and again have four 20-game losers.
  The Boston Americans finish last two years after winning the pennant.
  Cardinals' P Jack Taylor's record streak of 118 consecutive complete games ends on August 9.
  Ty Cobb leaves the Tigers to testify for his mother in her trial for shooting and killing his father.
• 1907
  The Cubs repeat as NL champs and this time win the World Series against the Tigers four games to none with one ending in a tie.
  Ty Cobb wins his first batting crown (.350) and first steals crown (49).
  Cleveland refuses a trade offered by Detroit–Elmer Flick for Cobb straight up.
  Chick Stahl, Boston AL player/manager, commits suicide during spring training.
  Philadelphia's Harry Davis wins the last of his four consecutive AL home run crowns. His winning number? Eight.
  The Pirates top the NL with a .254 BA, the lowest ever by an NL leader.
  Catching for the New York Highlanders, Branch Rickey allows a record 13 stolen bases to Washington on June 28.
  The Boston AL team is first called the "Red Sox."
• 1908
  This season produced two of the most thrilling–and controversial–pennant races in base­ball history. The two-team race in the National League required the replay of a game to settle it, and the American League stretch drive involved four teams.
  The New York Giants thought they had won the September 23 game with their archri­val, the Chicago Cubs, when SS Al Bridwell singled to center in the bottom of the 9th to score Moose McCormick from 3rd. But with jubilant fans overrunning the field, Fred Merkle, the runner on 1st, failed to touch 2nd. Chicago 2B Johnny Evers called for the ball and touched 2nd to force out Merkle and nullify the run. Since it was impossible to continue the game with the fans invading the field, NL president Harry Pulliam ordered the game replayed after the season if it made a difference. As luck would have it, the teams tied for 1st, and the Cubs won the replay 4-2 as Three Finger Brown outdueled Christy Mathewson.
  In the AL, a four-team race went down to the wire. Detroit finally slipped past Cleve­land by .004 percentage points, the smallest margin of victory in major league history. Chicago finished 1 1/2 back as St. Louis faded late to end up 6 1/2 behind.
  Detroit's Ty Cobb and Pittsburgh's Honus Wagner continued to dominate their respective leagues. As in 1907, Cobb and teammate Sam Crawford led the Junior Circuit in nearly everything. Cobb was #1 in batting average, hits, doubles, triples, total bases, RBI, and slugging. Crawford led in home runs and was second in runs, RBI, hits, total bases, batting, and slugging. Wahoo Sam is still the only player ever to be the home run leader in the AL and NL, having led the NL with 16 homers for the Reds in 1901. His title-winning total in '08? Seven. Despite this awesome one-two punch, the Tigers again lost the World Series to the Cubs, 4-1.
  Wagner won the NL batting title again with a .354 average. He also topped the league in on-base average, slugging %, hits, RBI, doubles, triples, total bases, and stolen bases.
  1908 was the biggest year for pitchers in a decade of dominant pitching. Both leagues batted. 239, record lows in both circuits. Only one of the 16 major league pitching staffs, the last place New York Highlanders, had an ERA over 3.00.
  Cleveland's Addie Joss twirled a perfect game against Chicago on October 2, the first ever in a pennant race.
  Walter Johnson of the Washington Senators pitched three shutouts in a four-day period vs the Highlanders.
  On September 26, Ed Reulbach of the Cubs pitched two shutouts in one day.
• 1909
  The first all-concrete-and-steel stadiums opened: Forbes Field in Pittsburgh and Shibe Park in Philadelphia.
  The Chicago Cubs won 104 games, more than they had in several pennant-winning years. But they finished 6 1/2 games behind the Pittsburgh Pirates, who went 110-42.
  The Pirates, led by SS Honus Wagner, scored a league-high 699 runs. Honus led the league in BA (.339), SA (.489), total bases (242), and RBI (100).
  The third-place New York Giants won 92 games, 15 more than the fourth-place Cincinnati Reds.
  In the American League, Detroit won their third-straight pennant as Ty Cobb won the Triple Crown, batting .377 with nine HRs and 107 RBIs.
  The World Series went the full seven games for the first time. Anyone expecting a great Wagner-Cobb match-up were disappointed. Honus had a decent Series, hitting .333, but Ty flopped, batting only .231. The teams alternated victories with the Pirates winning Game 7 behind rookie Babe Adams, a spot starter during the season who won all three games he pitched.
  Oddities:
  The Cubs beat the Boston Doves an NL record 21 times during the season.
  The Philadelphia Phillies were rained out a record ten straight days.
  Detroit and Washington played an 18-inning scoreless tie with Ed Killian going the route for the Tigers. That was one of 29 times during the season that the Senators were shutout - an AL record. Phillies C Red Dooin set a 20th-century NL record for catchers with 40 errors.
• 1910
  A record 46 minor leagues brought baseball entertainment across the nation.
  Comiskey Park opened in Chicago with a colossal capacity of 48,600. It would be the home of the White Sox until 1991. Cleveland inaugurated League Park as its new stadium.
  The Philadelphia Athletics ended Detroit's three-year reign as AL champions while the Cubs returned to the top of the NL with their fourth pennant in five seasons.
  Connie Mack's powerhouse team won the World Series in five games and would win the AL pennant another three times in the next four years.
  Jack Coombs led the A's with a 31-9 record and 1.30 ERA and won two games in the World Series, which Philly captured in five games.
  Oddities:
  President William H. Taft began the tradition of throwing out the first ball of the season in the nation's capital.
  Ed Walsh topped the AL in ERA at 1.26 but still lost 20 games as his White Sox hit a record-low .211 as a team.
  Steve Evans of the St. Louis Cardinals was hit by 31 pitches.
  The Chalmers Motor Company offered a car to the winner of the AL batting title. The race between Ty Cobb and Cleveland's Nap Lajoie went down to the last day. Since Cobb was hated throughout the league, the St. Louis Browns infield allegedly played deep to allow Nap to beat out seven bunts in a doubleheader on the last day to rob Cobb of the batting title .383 to .382.
• 1911
  Both leagues used the lively, cork-centered ball during the season, causing a hitting increase. The NL batted .260; the AL, .273, an increase of 30 points from 1910. Two AL teams, Philadelphia and Detroit, batted over .290.
  The NL team with the best batting average, the New York Giants, won the pennant. C Chief Meyers hit. 332; 2B Larry Doyle rapped 25 triples (still tied for fifth-best all-time). The Giants stole 347 bases, a modern record. The Cubs' pennant hopes took a blow when 2B Johnny Evers suffered a nervous breakdown in May. 37-year-old Honus Wagner won his final batting title by one point with a .334 average for the 3rd-place Pirates.
  In the AL, Connie Mack's Philadelphia powerhouse repeated as champions as they led their league in batting average just like the Giants. Second-to-last in ERA, Detroit's hitting led by Ty Cobb and Sam Crawford (first and second in RBI in the AL) kept them in first place for much of the first half of the season. Cobb led the league in runs, hits, doubles, triples, and stolen bases. He batted .420, 12 points better than Joe Jackson. The AL suffered its own tragedy when pitching legend Addie Joss died from meningitis. He compiled a 1.89 career ERA, the second-lowest in baseball history.
  In the World Series, A's 3B Frank Baker's nickname of "Home Run" became known nationwide when he hit two homers in the World Series to spark the six-game victory against the Giants.
  The Giants' home park, the Polo Grounds, was ravaged by fire and had to be rebuilt.
• 1912
  Hitting continued upward as the NL hit .272 and the AL, .265. Three of the Top Ten all-time triples totaled were achived by Ty Cobb (23), Joe Jackson (26), and Owen "Chief" Wilson (36, still the all-time record). Those numbers exceeded the top home run totals: Frank Schulte 21, Fred Luderus 16, and Sherry Magee 15.
  On the mound, Walter Johnson of the Washington Senators won 32 games and still trailed Smokey Joe Wood of the Red Sox, who won 34, including 16 in a row. However, Johnson's 1.39 ERA led the majors by a wide margin.
  Heinie Zimmerman of the Cubs led the NL in batting average, hits, homers, and doubles.
  The Boston Red Sox returned to the World Series for the first time since 1903, when they played the Pirates in the original Fall Classic. They beat the Giants in eight games (one game was ended by darkness in a tie) in one of the most interesting Series of all time.
  The Boston National League team changed its name for the second year in a row, this time from Rustlers to Braves. They had previously been the Doves, Beaneaters, and Red Stockings.
  Two new ballparks opened: Fenway Park in Boston and Navin Field (later Tiger Stadium) in Detroit.
  Eddie Collins of the A's stole six bases in a game twice in an 11-day period.

Source: 20th Century Baseball Chronicle: A Year-by-Year History of Major League Baseball