MLB Timeline & Abbreviations

start with the 1901 season teams: 
American League National League
Baltimore Orioles (1st) Boston Beaneaters
Boston Americans Brooklyn Superbas
Chicago White Sox Chicago Orphans
Cleveland Blues Cincinnati Reds
Detroit Tigers New York Giants
Milwaukee Brewers (1st) Philadelphia Phillies
Philadelphia As Pittsburgh Pirates
Washington Senators (1st) St Louis Cardinals
 
1902Milwaukee Brewers (1st) became St Louis Browns (current Orioles)
1902Cleveland Blues became Cleveland Bronchos (current Indians)
1903Baltimore Orioles (1st) became New York Highlanders (current Yankees)
1903Cleveland Bronchos became Cleveland Naps (current Indians)
1903Chicago Orphans became Chicago Cubs
1907Boston Beaneaters became Boston Doves (current Braves)
1908Boston Americans became Boston Red Sox
1909Boston Doves became Boston Rustlers (current Braves)
  
1911Boston Rustlers became Boston Braves
1913New York Highlanders became New York Yankees
1914Brooklyn Superbas became Brooklyn Robins (current Dodgers)
1915Cleveland Naps became Cleveland Indians
  
1932Brooklyn Robins became Brooklyn Dodgers
  
1943Philadelphia Phillies became Philadelphia Blue Jays
1945Philadelphia Blue Jays became Philadelphia Phillies
1946World Series went to 2-3-2 format
  
1953Boston Braves became Milwaukee Braves
1954St Louis Browns became Baltimore Orioles
1955Philadelphia A's became Kansas City A's
1958Brooklyn Dodgers became Los Angeles Dodgers
1958New York Giants became San Francisco Giants
  
1961Washington Senators (1st) became Minnesota Twins
1961Los Angeles Angels and new Washington Senators (2nd) began play
1962New York Mets and Houston Colt .45s began play
1965Houston Colt .45s became Houston Astros
1965Los Angeles Angels became California Angels
1966Milwaukee Braves became Atlanta Braves
1968Kansas City A's became Oakland A's
1969Each league separated into an East and West division
1969Montreal Expos and San Diego Padres began play
1969Seattle Pilots and Kansas City Royals began play
  
1970Seattle Pilots became Milwaukee Brewers
1972Washington Senators (2nd) became Texas Rangers
1977Toronto Blue Jays and Seattle Mariners began play
  
1985Division playoffs went from best-of-five to best-of-seven
  
1993Colorado Rockies and Florida Marlins began play
1994Each league became East, Central, and West divs with wild-card teams
1997California Angels became Anaheim Angels
1998Arizona Diamondbacks and Tampa Bay Devil Rays began play
1998Milwaukee Brewers switched from AL Central to NL Central
1998Detroit Tigers switched from AL East to AL Central
  
2005Montreal Expos became Washington Nationals
2005Anaheim Angels became Los Angeles Angels
2008Tampa Bay Devil Rays became Tampa Bay Rays
  
2012Florida Marlins became Miami Marlins
2012Second wild card team added in each league
2013Houston Astros moved from the NL Central to the AL West
 
List of abbreviations used in other pages:
Anaheim AnaAnaheim Angels (1997 - 2004)
Arizona AriArizona Diamondbacks (1998 - present)
Atlanta AtlAtlanta Braves (1966 - present)
Bal Orioles BlOBaltimore Orioles (1st) (1901 - 1902)
Baltimore BalBaltimore Orioles (1954 - present)
Bos Americans BsABoston Americans (1901 - 1907)
Bos Beaneaters BBnBoston Beaneaters (1901 - 1906)
Bos Bees BBeBoston Bees (1936 - 1940)
Bos Braves BsBBoston Braves (1911-1935, 1941-1952)
Bos Doves BsDBoston Doves (1907 - 1908)
Bos Rustlers BsRBoston Rustlers (1909 - 1910)
Boston BosBoston Red Sox (1908 - present)
Bkn Robins BkRBrooklyn Robins (1914 - 1931)
Bkn Superbas BkSBrooklyn Superbas (1901-1910, 1913)
Brooklyn BknBrooklyn Dodgers (1911-1912, 1932-1957)
California CalCalifornia Angels (1965 - 1996)
Chi Cubs ChCChicago Cubs (1903 - present)
Chi Orphans ChOChicago Orphans (1901 - 1902)
Chi White Sox ChWChicago White Sox (1901 - present)
Cincinnati CinCincinnati Reds (1901 - present)
Cle Blues CBlCleveland Blues (1901 - 1901)
Cle Bronchos CBrCleveland Bronchos (1902 - 1902)
Cle Naps ClNCleveland Naps (1903 - 1914)
Cleveland CleCleveland Indians (1915 - present)
Colorado ColColorado Rockies (1993 - present)
Detroit DetDetroit Tigers (1901 - present)
Florida FloFlorida Marlins (1993 - 2011)
Hou Colt .45s HoCHouston Colt .45s (1962 - 1964)
Houston HouHouston Astros (1964 - present)
Kansas City As KCAKansas City A's (1955 - 1967)
Kansas City KC Kansas City Royals (1969 - present)
LA Angels LAALos Angeles Angels (1961-1964, 2005-present)
LA Dodgers LADLos Angeles Dodgers (1958 - present)
Miami MiaMiami Marlins (2012 - present)
Mil Braves MlBMilwaukee Braves (1953 - 1965)
Mil Brewers MlWMilwaukee Brewers (1st) (1901)
Milwaukee MilMilwaukee Brewers (1970 - present)
Minnesota MinMinnesota Twins (1961 - present)
Montreal MtlMontreal Expos (1969 - 2004)
NY Giants NYGNew York Giants (1901 - 1957)
NY Highlanders NYHNew York Highlanders (1903 - 1912)
NY Mets NYMNew York Mets (1962 - present)
NY Yankees NYYNew York Yankees (1913 - present)
Oakland OakOakland A's (1968 - present)
Philadelphia AsPhAPhiladelphia A's (1901 - 1954)
Phi Blue Jays PhBPhiladelphia Blue Jays (1943 - 1944)
Philadelphia PhiPhiladelphia Phillies (1901 - present)
Pittsburgh PitPittsburgh Pirates (1901 - present)
San Diego SD San Diego Padres (1969 - present)
San Francisco SF San Francisco Giants (1958 - present)
Sea Pilots SePSeattle Pilots (1969)
Seattle SeaSeattle Mariners (1977 - present)
St Louis StLSt Louis Cardinals (1901 - present)
StL Browns StBSt Louis Browns (1902 - 1953)
TB Devil Rays TBDTampa Bay Devil Rays (1998 - 2007)
Tampa Bay TB Tampa Bay Rays (2008 - present)
Texas TexTexas Rangers (1972 - present)
Toronto TorToronto Blue Jays (1977 - present)
Washington WshWashington Nationals (2005 - present)
Wash Senators WSnWashington Senators (1st) (1901 - 1960)
Was Senators WsSWashington Senators (2nd) (1961 - 1971)