Before the 2008 Olympics in Beijing, the US had finished at the top of the gold medal count in four consecutive Olympics.
China snapped that streak in 2008, finishing with 51 gold medals to only 36 for the US. Without the benefit of home-field advantage, things returned to "normal" in London, with the US at 46 golds to China's 38.
America made up golds across all three major events: swimming (12 to 16), track and field (8 to 9) and gymnastics (2 to 3).
Most of the Chinese decline came from a slip in gymnastics (11 down to 5) and weightlifting (8 to 5). They maintained their powerhouse programs in table tennis, badminton and diving. They've been very good at finding "sports" like trampolining where it's pretty easy to turn money into medals.
They'd probably say the sheer number of swimming medals and relays unfairly tilts the tables towards the US. Either way, order has been restored to the universe.
For a complete breakdown, visit Sports Illustrated's medal count tracker.
For more on the Olympics, check out SB Nation's London 2012 Olympics hub.