Wikipedia:WikiProject Baseball/Team abbreviations

For current and former teams of current franchises:

Abbreviation/ Acronym	Franchise
ANA	Anaheim Angels
AZ	Arizona Diamondbacks
ATL	Atlanta Braves
BAL	Baltimore Orioles (original, 1901–1902; current, since 1954)
BOS	Boston Red Caps/Beaneaters (from 1876–1900) or Boston Red Sox (since 1953)
BSA	Boston Americans (1901–1907)
BSB	Boston Beaneaters (1901–1906) or Boston Braves/Bees (1912–1952)
BSD	Boston Doves (1907–1910)
BRS	Boston Red Sox (1908–1952)
BSR	Boston Rustlers (1911)
BKN	Brooklyn Dodgers/Robins/Superbas/Bridegrooms/Grooms/Grays/Atlantics
CAL	California Angels
CHC	Chicago Cubs (since 1903)
CHO	Chicago Orphans (1901–1902)
CHI	Chicago Orphans/Colts/White Stockings (1876–1900)
CWS	Chicago White Sox
CIN	Cincinnati Reds/Red Stockings
CLE	Cleveland Guardians/Indians/Naps/Broncos/Bluebirds/Lake Shores
COL	Colorado Rockies
DET	Detroit Tigers
FLA	Florida Marlins
HOU	Houston Astros/Colt .45s
KC	Kansas City Athletics (1955–1967) or Kansas City Royals (since 1969)
LAA	Los Angeles Angels (of Anaheim)
LAD	Los Angeles Dodgers
LA	Los Angeles Dodgers (1958–1961; 1965–2004)
MIA	Miami Marlins
MIL	Milwaukee Brewers (original; 1901) or Milwaukee Braves or Milwaukee Brewers (current; since 1970)
MIN	Minnesota Twins
MTL	Montreal Expos
NY	New York Gothams/Giants (1883–1902) or New York Yankees (1958–1961)
NYG	New York Giants/Gothams
NYM	New York Mets
NYY	New York Yankees
NYH	New York Highlanders
OAK	Oakland Athletics
PHA	Philadelphia Athletics
PHI	Philadelphia Phillies/Quakers (1883–1900; 1955–present)
PHP	Philadelphia Phillies (1901–1942; 1945–1954)
PHB	Philadelphia Blue Jays (1943–1944)
PIT	Pittsburgh Pirates/Alleghenys
SD	San Diego Padres
SEA	Seattle Mariners (since 1977) or Seattle Pilots (1969)
SF	San Francisco Giants
SLB	St. Louis Browns (AL)
SLC	St. Louis Cardinals (1902–1953)
STL	St. Louis Cardinals/Perfectos/Browns/Brown Stockings
TB	Tampa Bay (Devil) Rays
TEX	Texas Rangers
TOR	Toronto Blue Jays
WSH	Washington Senators (original, 1901–1960); (expansion, 1961–1971) or Washington Nationals (since 2005)