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A Brief History of MLB’s Expansion and How It Got to 30 Teams

Nate Cunningham

Brad Penner-Imagn Images
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MLB wasn’t always the massive league it is today. In the beginning, it was a smaller group of teams. While some teams trace their roots back to the Civil War era, MLB’s most-recent additions aren’t even 30 years old. 

The National League was founded in 1876 and the American League was established in 1901. Shortly after, in 1903, the two leagues reached an agreement and began a merger of sorts. 

The two leagues would remain legally separate until 2000, when they fully merged into one entity. At that time, the league had grown from 16 to 30 teams. 

Today, we’re breaking down how it all happened.

What is MLB Expansion?

The MLB’s expansion over the years resulted in the league not only growing its membership, but also expanding its reach across the country. Sort of fitting for America’s Pastime when you think about it. 

From 1903 until 1952, MLB had five markets with multiple teams (Boston, Chicago, New York City, Philadelphia and St. Louis) and just 16 teams in its ranks. Over the next five years, the Boston Braves moved to Milwaukee, the Philadelphia Athletics moved to Kansas City, the St. Louis Browns moved to Baltimore, the Brooklyn Dodgers moved to Los Angeles and the New York Giants moved to San Francisco. 

These relocations set in motion a series of events which led to MLB expanding coast to coast.

MLB Expansion History

By 1960, the plan was to double the number of MLB teams. Things started rather quickly with two teams, the Los Angeles Angels and the Washington Senators, joining in 1961. 

A year later, the Houston Colt .45s and New York Mets joined, bringing the league to 20 teams. In 1969, the Montreal Expos, San Diego Padres, Kansas City Royals and Seattle Pilots were part of another expansion. 

Now there were 24 MLB teams as the league entered the 1970s. So the league was well on its way toward doubling its membership. 

In 1977, the Seattle Mariners and Toronto Blue Jays joined, bringing the total number of teams to 26. And that’s where things would remain for the next 15 years, until the expansion boom of the 1990s. 

Four more franchises joined in the 1990s, first with the Colorado Rockies and Florida Marlins in 1993 and then the Arizona Diamondbacks and Tampa Bay Devil Rays in 1998. This brought MLB membership up to 30 teams and it has remained that way since. 

However, the league still hasn’t reached its original goal of doubling in size. But that doesn’t mean there aren’t cities vying for membership. 

Could MLB Expand Again?

In all likelihood, MLB is probably close to expanding again. By 2030, it seems inevitable that at least one, but perhaps two, new teams will be announced. 

The current frontrunners appear to be Nashville and Salt Lake City. 

Both cities are top-30 markets in the U.S., both are among the fastest-growing cities in America (according to census data) and both have high-power players working to pitch MLB. 

Music City Baseball in Nashville has already started a market analysis on a new stadium and Big League Utah has apparently made a strong impression on MLB officials with thorough and complex planning. 

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Nate Cunningham
NATE CUNNINGHAM

Nathan Cunningham is a writer for Sports Illustrated and Minute Media. Throughout his career, he has written about collegiate sports, NFL Draft, Super Bowl champions, and more. Nathan has also been featured in FanSided and 90Min. Nathan loves colorful uniforms, mascots and fast-break pull-up 3-pointers. He graduated from BYU in 2016 with a degree in journalism.

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