Since its birth in 1962, Houston’s MLB franchise had been a National League staple, but the Astros volunteered for a switch after 51 years as a National League franchise.
The team made their American League debut with an 8-2 win over their new AL West rivals from Dallas, the Texas Rangers.
Since 1998, there had been 16 teams in the NL and 14 in the AL. To balance the leagues, Houston was chosen to make the move, especially because of the instant rivalry with the Rangers. The other reason was that the Astros were for sale, and MLB figured prospective buyers would be anxious to please.
The Astros’ first season in the American League ended up as the worst season in franchise history, with a whopping 111 losses.
After a total rebuild, the Astros had another bad season in 2014, but they made the playoffs in 2015. And by 2017, they had a World Series championship.
This movement was precedent for switching leagues in modern Major League Baseball. The Milwaukee Brewers, after 29 years in the American League, moved to the National League in 1998.
