Cummings, who has four goals in his last five games, dribbled the ball inside the penalty area, where he fired a low shot past goalkeeper Ray Burse. The Rapids (5-2-6), 3-0-5 during their unbeaten stretch, bettered the previous mark of seven matches established April 10-May 27, 1999, and equaled Aug. 16-Oct. 2, 2003.
Colorado's last loss was a 1-0 defeat April 19 at Houston.
David Ferreira scored in the 37th minute for Dallas (3-7-5).
Despite being dominated in the first half, Dallas grabbed the lead on Ferreira's goal. Kenny Cooper sent a pass to Jeff Cunningham, who nudged the ball ahead to Ferreira outside the goal box, where he beat goalkeeper Matt Pickens for his second goal of the year.
Colorado had several chances to break open the game before Ferreira's goal. But Burse dived to swat away a shot by Nick LaBrocca in the 15th minute and knocked away a shot by Colin Clark from 25 yards in the 16th.
Clark missed wide right from just inside the penalty area in the 24th minute, and LaBrocca's header in the 45th sailed over the crossbar.
Each team had a quality chance in the second half. Burse caught Cory Gibbs' shot in the 55th minute, while Pickens smothered a shot in the 66th by Andre Rocha, who got behind Colorado's defense for a breakaway.
Ugo Ihemelu missed on a header in the 81st minute for Colorado.