The Houston Astros are an American professional baseball team based in Houston, Texas. The Astros compete in Major League Baseball (MLB) as a member club of the American League (AL) West division, having moved to the division in 2013 after spending their first 51 seasons in the National League (NL). The Astros have played their home games at Minute Maid Park since 2000.

Can we conclude that did houston astros used to be in national league?
yes