That does not mean the two nations are not connected, of course. China’s rebound in growth may slow if the American economy does not pick up. China needs the United States to buy its goods, and the United States needs China to continue to buy its debt.

This mutual dependence makes it harder for either country to let the current dispute over Chinese tires and American chicken and auto parts to grow into a trade war.

But with more centralized economic planning than the United States, China has been able to disburse its stimulus much faster, turning it into new rail lines and highways.

China’s finance ministry announced in late June that half the $173 billion in central government spending had already been allocated to specific projects. The White House said in early July that a quarter of the spending authority and tax cuts in the $789 billion American stimulus had been allocated or used.

But even more key to China’s recovery, economists say, are two other government efforts that are paying big dividends: looser lending and export supports.

The state-controlled banking system here  which breezed through the global financial crisis with minimal losses as American financial institutions reeled  unleashed $1.2 trillion in extra lending to Chinese consumers and businesses in the first seven months of this year. That money is financing everything from a boom in car sales, up 82 percent in August from a year earlier, to frenzied factory construction.

Beijing also has given huge tax breaks and other assistance to exporters. They include placing broad restrictions on imports and intervening heavily in currency markets to hold down the value of the renminbi, to keep Chinese exports competitive even in a weakened global economy.