The U.S. teams also won the most gold medals, taking 46 to China's 38. Great Britain, which hosted the Olympics, placed third for gold medals with 29.
The Russian team placed third for overall medals with 82, but won more bronze medals (33) than gold (24).
The U.S. team also won the most silver medals, with 29. China had the second most silver medals, with 27; and Russia was third with 25.
The U.S. Olympic success was led by male and female swimmers, who dominated the London games.
The U.S. won 16 gold medals in swimming alone. After swimming, the second most U.S. gold medals came in track and field events, where U.S. athletes won 9 golds.
Michael Phelps, who said he was competing in his last Olympics, won 6 medals in swimming, including 4 golds and 2 silvers. Phelps took individual gold medals in the 100-meter butterfly and the 200-meter medley. Phelps also won gold medals in the 400 times 100-meter medley relay and 4 times 200 freestyle relay.
Twenty-two-year-old Allison Schmitt of Canton, Mich., also won five swimming medals, including 3 golds, a silver and a bronze. Schmitt won golds in the 200-meter free-style, the 4 times 200-meter freestyle relay, and the 4 times 100-meter medley relay. She won a silver in the 400-meter freestyle and a bronze in the 4 times 100-meter freestyle relay.
Allyson Felix of Los Angeles, Calif., won three gold medals on the track. Felix won golds in 200-meter race, the 4 times 100-meter relay and the 4 times 400-meter relay.
Twenty-four-year-old Dana Vollmer of Granbury, Texas, also won three gold medals in the pool for the U.S.A. Vollmer won the 100-meter butterfly, and swam legs on the gold-medal winning team for the 4 times 100-meter medley relay and the 4 times 200-meter freestyle relay.
Sonya Richards-Ross, 27, of Ft. Lauderdale, Fla., won the gold medal in the 400-meter race, and took another gold medal as part of the 4 times 400-meter relay team.
Aly Raisman of Needham, Mass., won three medals in gymnastics, including the gold medal for the floor exercise and another as part of the U.S. women's gold medal gymnastics team. She also won a bronze on the balance beam.
Sixteen-year-old Gabby Douglas, of Virginia Beach, Va., also won two golds. One as a member of the champion U.S. women's team and another in individual all-around gymnastics competition.
When Douglas won her gold medal she said: "I give all the glory to God."
Top Ten medal-Winning Nations London Olympics
1. United States.......104 medals (46 gold, 29 silver, 29 bronze)
2. China....................87 medals (38 gold, 27 silver, 22 bronze)
3. Russia...................82 medals (24 gold, 25 silver, 33 bronze)
4. Great Britain.........65 medals (29 gold, 17 silver, 19 bronze)
5. Germany..............44 medals (11 gold, 19 silver, 14 bronze)
6. Japan...................38 medals (7 gold, 14 silver, 17 bronze)
7. Australia..............35 medals (7 gold, 16 silver, 12 bronze)
8. France.................34 medals (11 gold, 11 silver, 12 bronze)
9. South Korea........28 medals (13 gold, 8 silver, 7 bronze)
10. Italy..................28 medals (8 gold, 9 silver, 11 bronze)