In the past month, both Venezuela and Bolivia expelled the American ambassadors to their countries. Not only did Brazil, thought to be among America’s strongest allies in the region, support the expulsion by Bolivia, a major source of natural gas, but Mr. da Silva also railed against an American naval presence in the region, warning that his nation needed to put its own warships on alert in response.

Such anti-American sentiment reflects a longstanding bitterness over Washington’s economic prescriptions for Latin America, policies that some countries in the region blame for undercutting them. As Wall Street itself started to unravel, some leaders seemed to feel vindicated by the collapse.

“We are witnessing the First World, which at one point had been painted as a mecca we should strive to reach, popping like a bubble,” Cristina Fernández de Kirchner, Argentina’s president, said two weeks ago.

But the financial crisis has exploded far beyond Wall Street. Whipsawing global markets are already having a ripple effect across Latin America. As nervous investors pulled money out of emerging markets, Brazil’s currency, the real, plunged 16 percent against the dollar last month, resulting in hundreds of millions of dollars in losses at large food and eucalyptus-pulp exporters that placed bad bets on the direction of the real.

In Mexico, falling remittances from the United States are also raising concern, with Finance Minister Augustín Carstens warning that money sent home from across the border could decline by $2.8 billion, or 8 percent, this year. In Venezuela, a sharp drop in the value of the country’s bonds in the last two weeks reflects fears about plunging oil prices, especially since the United States remains by far the largest buyer of Venezuelan oil despite the deterioration of relations between the countries.

The issue, economists say, is largely about access to credit, which is needed to keep Latin America’s export-oriented economies humming along. “The credit crunch and the liquidity constraints we are seeing are going to affect everyone in the world,” said Alfredo Coutiño, a senior economist at Moody’s, the credit-rating agency. “That means that the cost for Latin American companies, particularly for those with the need for external funds, is going to be higher.”