The 2004 MLS season was a landmark year that featured several historic milestones. DC United won their fourth MLS Cup title, defeating the Kansas City Wizards 3-2 in the final played at The Home Depot Center (now Dignity Health Sports Park) in Carson, California. This victory tied DC United with the LA Galaxy for most MLS Cup championships at the time.
The season was notable for the emergence of teenage phenom Freddy Adu, who became the youngest player in MLS history when he debuted at age 14 for DC United. Adu's signing generated unprecedented media attention and helped raise the profile of Major League Soccer significantly. The New England Revolution also had a strong season, winning the Supporters' Shield for the best regular season record.
Other significant storylines included the continued growth of soccer-specific stadiums, with several teams playing in newly built venues. The season featured 10 teams playing a 30-game regular season schedule, maintaining the same format as previous years. Notable individual performances included strong seasons from established stars like Carlos Valderrama and Landon Donovan, who helped drive league attendance and television viewership to new heights.