Seattle tied it 2 on an own goal by Dallas' Stephen Keel in the 75th minute.
The goal came after Dempsey attempted a cross from the right side that bounced off of the side of Keel's leg and into the left corner of the net. Dempsey's first goal came off a free kick in the 22nd minute after he fired a bending shot that landed just inside the goal line to tie it at 1.
United 1, Red Bulls 0 • In Washington, Davy Arnaud scored on a diving header in the fourth minute in D.C. United's victory over New York.
After snapping a club-record 15 game winless streak last week, United has won consecutive games for the first time since the end of the 2012 season.
Rapids 1, Toronto FC 0 • Former Toronto forward Edson Buddle scored his 99th MLS goal from close range in the 77th minute to help Colorado win in Toronto.
Rapids scoring leader Vicente Sanchez missed the game to remain in Colorado because his wife is expecting their first child.