“This is a vote of confidence in the American economy, the American marketplace and the American worker,” the deputy Treasury secretary, Robert M. Kimmitt, said. “These investments keep Americans employed and keep balance sheets strong.”

Five million Americans now work for foreign companies set up in the United States, Mr. Kimmitt said, and those jobs pay 30 percent more than similar work at domestic companies. Nearly a third of such jobs are in manufacturing, which explains why Rust Belt states have been wooing foreign investment.

“We’ve lost 400,000 manufacturing jobs,” said Michigan’s governor, Jennifer M. Granholm, a Democrat, who has traveled three times to Europe and twice to Japan in pursuit of investment since taking office in 2003. “I’ve got to get jobs for our people.”

Some labor unions see the acceleration of foreign takeovers as the latest indignity wrought by globalization.

“It’s the culmination of a series of fool’s errands,” said Leo W. Gerard, international president of the United Steelworkers. “We’ve hollowed out our industrial base and run up this massive trade deficit, and now the countries that have built the deficits are coming back to buy up our assets. It’s like spitting in your face.”

Other labor groups take a more pragmatic view.

“We need investment and we need to create good jobs,” said Thea Lee, policy director for the A.F.L.-C.I.O. in Washington. “We’re not in the position to be too choosy about where that investment comes from. But it does bring home the consequences of flawed trade policies over many, many years that we’re in this position of being dependent.”

At the center of concern is the growing influence of sovereign wealth funds, which invested $21.5 billion in American companies last year, according to Thomson. Analysts say they could skew markets by investing to improve the fortunes of their national companies or to pursue political goals.

“This is a phenomenon that could be called the growth of state capitalism as opposed to market capitalism,” said Jeffrey E. Garten, a trade expert at the Yale School of Management. “The United States has not ever been on the receiving end of this before.”

Perhaps emblematic of national ambivalence, in an appearance on CNBC last week, the voluble market analyst Jim Cramer spoke in menacing terms about the growing role of state investment funds from the Middle East and China.

“Do we want the communists to own the banks, or the terrorists?” Mr. Cramer asked. “I’ll take any of it, I guess, because we’re so desperate.”

Proponents of investment from overseas note that finance from sovereign wealth funds is a mere trickle of the overall flow from abroad. Indeed, the bulk comes from Europe, Canada and Japan. Just as Americans have scattered investments around the world in pursuit of profit — with holdings of foreign stock and debt exceeding $6 trillion in 2006, according to the Treasury Department — foreigners are looking to the United States, with their capital generating economic activity, proponents say.

If fear of foreign money now inspires Americans to erect new barriers, that would damage the economy, said Todd M. Malan, president of the Organization for International Investment, a Washington lobbying group financed by foreign companies.

“The policy choices on the negative side would have enormous economic implications that would make the current situation look like a bubble bath,” he said.

Tensions spawned by foreign investment hark back to the 1980s, when Japan snapped up prominent American businesses like Columbia Pictures, and some intoned that the American way of life was under assault. The new wave of foreign money is washing in at an even more important time, analysts say.

The United States has lost more than three million manufacturing jobs since 2001, with foreign trade often taking the blame. Foreign-made goods now account for roughly one-third of all wares consumed in the United States, roughly tripling their share over the last quarter-century. The soaring price of oil and a widening trade deficit underscore how the American economy is increasingly vulnerable to decisions made far away.