San Jose (5-6-3, 18 points) kept its resurgence alive after starting the season 0-4, while D.C. (7-4-6, 27 points) has gone without a win in the last five games.
A first-half goal from Chris Wondolowski for San Jose and a second half D.C. tally from Luciano Acosta accounted for the two goals.
After a first half where San Jose easily had the run of play and a 1-0 lead, D.C. flipped a switch and took it to the Earthquakes in the second half.
In a span of two minutes early in the second half, San Jose goalie Daniel Vega made three big saves to keep the lead.
In the 55th minute, Vega was up to the task on a pair of shots from Acosta and Leonardo Jara, making a pair of diving deflections. A few minutes later, Vega made a sensational save off a Junior Moreno volley from 18 yards out.
But as good as Vega was for that sequence, it was a mistake 10 minutes later that allowed D.C. to tie it.
Jara launched one from 30 yards out. Vega went down to make the save, but instead of keeping it under control, he knocked it away, allowing Acosta to charge in, get the rebound and tie it 1-1.
Wondolowski gave San Jose a 1-0 lead in the 37th minute with his seventh goal in the last three games, knocking home a head shot off a cross from Nick Lima. Wondolowski snuck in behind D.C. defender Jalen Robinson, who got caught napping.
The goal gave the all-time leading MLS goal scorer 151 for his career.
It was fitting that the Earthquakes led at the break as the team fully dominated the first half, outshooting D.C. 17-3 in the first 45 minutes, including a 6-0 edge for shots on target.
D.C. United back atop Eastern Conference after 1-1 draw
Luciano Acosta's second half strike was enough to seal a 1-1 draw with San Jose, moving them temporarily atop MLS's Eastern Conference.