Major League Baseball can trace its roots back to 1869 with the two major leagues, the National League (founded in 1876) and the American League (founded in 1901).
Many of the original teams can trace their lineage even further back that the cutoff date of 1903, widely considered to be the start of the modern era of Major League Baseball.
AL East
Baltimore Orioles: St. Louis Browns (1902-1953), Baltimore Orioles (1954-present)
Boston Red Sox: Boston Americans (1901-1907), Boston Red Sox (1908-present)
New York Yankees: New York Highlanders (1903-1912), New York Yankees (1913-present)
Tampa Bay Rays: Tampa Bay Devil Rays (1998-2007), Tampa Bay Rays (2008-present)
Toronto Blue Jays: Toronto Blue Jays (1977-present)
AL Central
Chicago White Sox: Chicago White Sox (1901-present)
Cleveland Indians: Cleveland Naps (1903-1914), Cleveland Indians (1915-present)
Detroit Tigers: Detroit Tigers (1894-present)
Kansas City Royals: Kansas City Royals (1969-present)
Minnesota Twins: Washington Nationals/Senators (1901-1960), Minnesota Twins (1961-present)
AL West
Los Angeles Angels (of Anaheim): Los Angeles Angels (1961-1965), California Angels (1965-1996), Anaheim Angels (1997-2004), Los Angeles Angels of Anaheim (2005-present)
Oakland Athletics: Philadelphia Athletics (1901-1954), Kansas City Athletics (1955-1967), Oakland Athletics (1968-1969), Oakland A’s (1970-1980), Oakland Athletics (1981-present)
Seattle Mariners: Seattle Mariners (1977-present)
Texas Rangers: Washington Senators (1961-1971), Texas Rangers (1972-present)
NL East
Atlanta Braves: Boston Beaneaters (1883-1906), Boston Doves (1907-1910), Boston Rustlers (1911), Boston Braves (1912-1935), Boston Bees (1936-1940), Boston Braves (1941-1952), Milwaukee Braves (1953-1965), Atlanta Braves (1966-present)
Miami Marlins: Florida Marlins (1993-2011), Miami Marlins (2012-present)
New York Mets: New York Mets (1962-present)
Philadelphia Phillies: Philadelphia Phillies (1883-present)
Washington Nationals: Montreal Expos (1969-2004), Washington Nationals (2005-present)
NL Central
Chicago Cubs: Chicago Cubs (1903-present)
Cincinnati Reds: Cincinnati Reds (1890-1953), Cincinnati Redlegs (1953-1958), Cincinnati Reds (1958-present)
Houston Astros: Houston Colt .45s (1962-1964), Houston Astros (1965-present)
Milwaukee Brewers: Seattle Pilots (1969), Milwaukee Brewers (1970-present)
Pittsburgh Pirates: Pittsburgh Pirates (1891-1911), Pittsburgh Pirates (1912-present)
St. Louis Cardinals: St. Louis Cardinals (1900-present)
NL West
Arizona Diamondbacks: Arizona Diamondbacks (1998-present)
Colorado Rockies: Colorado Rockies (1993-present)
Los Angeles Dodgers: Brooklyn Superbas* (1899-1910), Brooklyn Robins* (1914-1931), Brooklyn Dodgers (1932-1957), Los Angeles Dodgers (1958-present)
* Denotes unofficial nickname of Brooklyn based ballclub
San Diego Padres: San Diego Padres (1969-present)
San Francisco Giants: New York Giants (1885-1957), San Francisco Giants (1958-present)
Sources:
All data provided by MLB.com
Paul Rados is a Cleveland based freelance sportswriter and Featured Contributor for the Yahoo! Contributor Network. Follow him on Twitter @PSRados or leave him a message on Facebook. For a complete look at his freelance work please visit his Blog.