2013 Houston Astros season

The 2013 Houston Astros season was the 52nd season for the Major League Baseball (MLB) franchise located in Houston, Texas, their 49th as the Astros, and 14th at Minute Maid Park. Further, it was the Astros' inaugural season as members of both the American League (AL) and AL West division, after having spent their first 51 seasons in the National League (NL). The Astros entered the season with a 55–107 record and last-place finish in the NL Central division, 42 games behind the division-champion Cincinnati Reds, Houston's worst-ever record to date, as well the second consecutive of the first two 100-loss seasons in franchise history.

The 2013 season was the first for Bo Porter as manager, the 21st in Astros' franchise history, succeeding Tony DeFrancesco. On March 31, the Astros won their first Opening Day as an American League team, 8–2, while hosting their in-state rivals, the Texas Rangers. Bud Norris was the Astros' Opening Day starting pitcher. It was also the 4,000th win in franchise history.

In the first round of the June MLB draft, the Astros selected pitcher Mark Appel as the first overall pick.

Catcher Jason Castro represented the Astros at the MLB All-Star Game and played for the American League, his lone career selection. On July 19, outfielder Brandon Barnes hit for the cycle while going 5-for-5 for the eighth cycle in franchise history.

The Astros concluded their regular season with a 51–111 record, in last place the AL West, 45 games behind the Oakland Athletics, and worst record in the major leagues. This continued Houston's downward trend starting in 2010 into an unprecedented third 100-loss season, having won 4 fewer than year prior to establish another new club record for losses. This was fewest wins by any MLB club since the 2004 Arizona Diamondbacks, who had an identical 51–111 record. The Astros set another club record by finishing 45 games out of first place to surpass the 1975 team, who placed 43+1⁄2 games behind the NL West division-champion Reds.