The Seattle Sounders were far too strong for MLS rivals the Colorado Rapids, winning 4-1 away from home on Sunday.
Clint Dempsey (penalty), Obafemi Martins and Marco Pappa all netted for the Sounders inside 33 minutes and although Deshorn Brown pulled a goal back two minutes before half-time, Martins got his second goal of the game 20 minutes from the end.
The result means the Sounders join the Los Angeles Galaxy on 60 points at the top of the Western Conference.
Real Salt Lake are now 11 points behind the leaders after Felix Borja's 47th-minute goal for bottom club Chivas USA inflicted a 1-0 defeat on the third-placed side.
The Eastern Conference's bottom two, Chicago Fire and Montreal Impact, drew 0-0 in Sunday's other match.
Source: FIFA.com