The Expansion Era saw the Major Leagues grow from 16 teams in 1959 to 24 teams in 1975. The Washington Senators moved to Minnesota in 1960, and MLB decided to expand earlier than planned at risk of losing its anti-trust exemption. The new Washington Senators would become the Texas Rangers in 1972. They were joined by the Los Angeles Angels in the same year. 1962 saw the Houston Colt .45s and the New York Mets join the Majors, followed by the Kansas City Royals, Seattle Pilots (later to become the Milwaukee Brewers), San Diego Padres, and the international addition of the first Canadian Team, the Montreal Expos.
I cut off the Expansion Era at 1975, right before Free Agency took hold, but there were two new teams formed in 1977: the Seattle Mariners, and the Toronto Blue Jays.
If you looked at a map of the MLB in 1950, this is what it would look like:
The same map in 1977 after Expansion was finished would look like this:
The Expansion era also saw a couple rule changes. The pitching mound was lowered in 1968, and the Designated Hitter rule was introduced in 1973. Baseball looks more and more like the modern game. Integration sees the rise of all-time great non-white players like Hank Aaron and Willie Mays. Let’s take a look at those players:
Who jumps out to you?
Player list (career WAR in parentheses):
- Fangraphs Career WAR Leaders