Dike's goal came after Steven Smith's cross was initially stopped by D.C. midfielder Marcelo Saragosa. But the Timbers forward corralled the ball and fired it into the net, erasing a 1-0 deficit.
Portland, out of the playoffs, improved to 7-15-9.
Chris Pontius scored on a controversial penalty kick for United (15-10-6), which drew closer to a playoff berth with the draw.
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