LONDON -- By the time Allyson Felix was done doing her part, her third gold medal of the Olympics was all but hanging around her neck.
Staking the U.S. team to more than a 2-second lead at the halfway point Saturday night, then watching Sanya Richards-Ross bring home the blowout victory, Felix added the 4x400-meter relay gold to those she had won earlier in the 4x100 relay and 200-meter sprint.
"By the time I got the stick," Richards-Ross said, "it was basically a victory lap."
The United States finished in 3 minutes, 16.87 seconds -- good for a 3.36-second rout over Russia, the biggest margin in the final of the long relay at the Olympics since East Germany beat the U.S. by 3.58 seconds in 1976.
Jamaica took third in 3:20.95.
The U.S. extended its winning streak in this race to five straight, dating to 1996.
Felix became the first U.S. woman to win three golds in Olympic track since 1988, when Florence Griffith-Joyner won the 100, 200, and 4x100 relay in Seoul.
Felix's victories came half a world away, though she's now in the same stratosphere with some of the U.S. greats.
"London is very special to me," Felix said.
The gold Felix really wanted was in the 200-meter sprint that eluded her in Athens and Beijing. After that, everything else was gravy in Britain, though Felix was hardly going through the motions in her last race of the games.
Handed about a 10-meter lead by teammate DeeDee Trotter, Felix ran the second leg in 47.8 seconds -- 1.8 seconds faster than Russia's Antonina Krivoshapka -- to put a huge swath of track between her and the Russians before she handed off to Francena McCorory.
McCorory expanded the lead by another .49 seconds, then delivered it to Richards-Ross, who was basically running alone, loosely holding onto the baton as she breezed across the finish line.
"The ladies were phenomenal," Richards-Ross said. "They made it too easy for me."
When it was over, Richards-Ross tucked the stick under her arm and started clapping. Then, one-by-one, Felix, Trotter and McCorory came over and the whole group embraced, huddling with their arms around each others' shoulders.
"It's unbelievable," Felix said. "I think about how I ended in Beijing, just feeling discouraged there. Four years later to have all this happen, to really accomplish every goal that I set out, is such a blessing."
It marked yet another success for a U.S. track team that had pegged 30 as the goal to reach. After Felix and her teammates were finished, the men's 4x100 relay team and high jumper Brigetta Barrett both took silver to lift the U.S. team to 29. The marathon closes out the track schedule today, with 2004 silver medalist Meb Keflezighi in the race.
"I think the pressure was on to go out and do what we are capable of doing," Trotter said of the 30-medal goal. "I think we finally hit the mark this time. We hit the center of the target. We got it done."
The track meet could have been an even more rousing success for the U.S. had the men done more in the sprints they dominated for decades, until Usain Bolt came around.
But that's not Felix's fault.