The National Association of Base Ball Players (NABBP) was the first organization to govern baseball.
In 1876 six clubs from the NA and two independents joined to create the National League (NL).
All of the 1899 Western League teams were a part of the transformation with the Saint Paul Apostles moving to Chicago to play as the White Stockings.
For its inaugural major league season the AL dropped its teams in Indianapolis, Buffalo and Minneapolis and replaced them with franchises in Boston, Philadelphia, and Baltimore.
Due to the 1994–95 Major League Baseball strike, there were no pennant or World Series winners in 1994, so this year is left blank.
MLB realigned to three divisions in each league to accommodate an expanded postseason format with a wild card team (although this new playoff format would not be fully implemented until 1995 due to a work stoppage): The California Angels became the Anaheim Angels.
In this realignment: By December 2001, this plan was scrapped; both teams would be retained for the following season.
With interleague play expanded to occur throughout the season, the Houston Astros transferred to the AL West to accommodate each league with 15 clubs apiece.
The Oakland Athletics temporarily moved to West Sacramento, California, and branded themselves as simply the "Athletics" and "A's" with no city name attached, until they permanently relocate to Las Vegas in 2028 or later when their new ballpark is completed.