The U.S. economy during the third quarter grew at its fastest pace in nearly two decades, but area leaders said that doesn’t necessarily translate into a booming Lawrence economy.

Gross domestic product, the broadest measure of the economy’s performance, grew at a breakneck 7.2 percent annual rate during the July-September period, more than double the 3.3 percent rate in the previous quarter, the Commerce Department reported Thursday. Both consumers and businesses helped power the gains, fresh evidence the national rebound is on firmer footing.

“Consumers were buying everything from cars and clothes to homes, and businesses are seemingly coming out of their cocoon,” said Mark Zandi, chief economist at Economy.com.

Area economic experts, however, were more cautious about the Lawrence economy’s turnaround.

“I certainly don’t think firms in Lawrence have had their output grow by 7 percent,” said Luke Middleton, an economist with Kansas University’s Policy Research Institute. “I just don’t think that is happening here.”

Lawrence retailers had mixed thoughts Thursday about whether consumers were spending more.

“In my opinion, we’re about flat,” said Brett Schubert, store team leader for SuperTarget, 3201 Iowa. “I’d say our overall foot traffic is even down.”

But at Office Depot, 2525 Iowa, store manager Mike Lang said the store was ahead of projections it had made for the year and that both transactions and traffic counts were better than the previous year’s totals.

Economists said that near rock-bottom, short-term interest rates, along with President Bush’s third round of tax cuts, induced consumers and businesses to spend and invest more and helped the economy move at a faster clip during the summer.

The next challenge is making sure the rebound is self-sustaining, they said.

“Job growth is the key to a sustained economic expansion,” said Bill Cheney, chief economist at Boston-based John Hancock. “If people are worried about their jobs, or worse, if they are getting laid off, then consumer spending is at risk.”

There are some signs that the employment picture is gradually improving in Lawrence, Middleton said. He said the area’s unemployment rate, which in September was 4.0 percent, had returned to the pre-recession levels of 2000.

“But those numbers need to stay there for a longer period of time before I’m comfortable saying it is a trend,” Middleton said.

Nancy Slabaugh, district manager of Lawrence’s Manpower employment office, said she was seeing more of her customers converting temporary workers into permanent employees, which usually is a sign of growing business confidence.

“I think we’re finally starting to add some jobs in Douglas County,” Slabaugh said.