The 2015 Major League Soccer season featured 20 total clubs (17 based in the United States, 3 based in Canada). The regular season was held from March 6 through to October 25, whereas the MLS Cup Playoffs began on October 28 and ended with MLS Cup 2015 on December 6. The defending MLS Cup champions were the LA Galaxy, while Seattle Sounders FC were the defending Supporters' Shield winners.