Major League Baseball, like many other large sports groups, is a franchisor. What this means is that expansion teams are only added when they pay to be part of the group, bringing a new city into the mix as a potential champion.
When the league was formed there were only 16 teams, all of which were in the east and St. Louis. But between the leagues inception and today the population of the west has more than doubled. Those residents of Oakland, San Francisco, Denver, Phoenix, LA and other Western cities wanted representation, too. Some eastern teams moved west (SF Giants) but most didn’t want to. What were the cities to do? They got expansion teams.
Expansion teams generally perform terribly during their first few seasons. New teams don’t have the money to bring big names to their cities, and because they are new they have last choice in the draft. What that means is that the handful of new expansion teams are competing against one another to get the best of a mediocre lineup of talent. It is not impossible to succeed within a few years, though: the Arizona Diamondbacks were founded in 1998 and they won the World Series in 2001. That said, this is the exception to the rule.
The first two expansion teams were brought in 1961, and the MLB has been seeing additions every few years since then. The most recent additions were in:
- 1998. Today’s team roster has gone up from its original 16 to 30.
- 1961: LA Angels of Anaheim (brought in as Anaheim Angels) and Texas Rangers (originally Washington Senators)
- 1962: Houston Astros (formerly Houston Colt.45′s) and the New York Mets
- 1969: Washington Nationals (signed on as the Montreal Expos), the San Diego Padres, Kansas City Royals and Milwaukee Brewers (who started as the Seattle Pilots)
- 1977: The Seattle Mariners and the Toronto Blue Jays
- 1993: Colorado Rockies and the Florida Marlins
- 1998: Arizona Diamondbacks and Tampa Bay Rays (formerly the Tampa Bay Devil Rays)