[5] After spending the 2010 season with Crystal Palace Baltimore, Bush signed with Montreal Impact of the North American Soccer League on March 11, 2011.

[9][10] Bush was awarded the 2011 Golden Glove, which is given to the goalkeeper with the best goals-against average in the NASL, and finished the year with nine shutouts, including seven in the final 10 games of the season.

[8] Bush signed a contract with the Montreal Impact to remain with the club for their inaugural season in Major League Soccer on October 21, 2011.

[13] The 2015 season was a breakthrough for Bush, as he was Montreal's number one goalkeeper,[14] helping guide his club to the final of the Champions League.

Bush showed his frustration for the call after the match, saying "After every goal I give up, I kick the ball towards midfield.

[19] During the 2021 season, Bush made five total appearances for the Crew, including the 2–0 shutout of Cruz Azul in the Campeones Cup.