Not long ago, the United States was considered the tortoise of the world economy, at least in comparison to emerging powers like China and Brazil.

Lately, however, slow but steady seems to be winning the race. The American economy continues to chug along, while the onetime hares in Asia, South America and elsewhere are flagging.

The latest evidence of this shift came on Thursday, as the Commerce Department revised sharply upward its estimate of economic growth in the second quarter to a healthy annual pace of 3.7 percent, from an initial estimate of 2.3 percent. At the same time, the Labor Department, in reporting another drop in weekly unemployment claims, provided further evidence that the job market was on the mend.

Stocks on Wall Street jumped by nearly 2.5 percent on Thursday, following a broader 4 percent rebound on Wednesday. Oil prices also rallied by almost 10 percent to settle above $40 a barrel after sinking to postrecession lows earlier in the week.