Exports, one of the flailing economy's few solid pillars, appears to be weakening.

Overseas shipments by U.S. companies fell 2.3% to a seasonally adjusted $171 billion in June from May, the Census Bureau reported Thursday. It was the second monthly decline in a row and a sharp drop that reflects a slumping global economy. Imports, meanwhile, dipped 0.8% to $224 billion.

As a result, the trade deficit widened by $2.3 billion to $53.1 billion, the largest gap since October 2008.

"It's worrisome because (exports) had been one of the brighter spots," says Diane Swonk, chief economist at Mesirow Financial.

A separate job market report was more encouraging.

The Labor Department said the number of Americans making initial claims for jobless benefits last week fell below 400,000 for the first time since April.

The disappointing export report will likely chop the government's meager 1.3% estimate for second-quarter economic growth to less than 1%, says economist Gregory Daco of IHS Global Insight.

The gloom could persist into next year. Swonk says she recently revised her forecasts for 2012 export growth to about 8% from 12%.

Exports make up about 13% of the economy but, along with manufacturing and business investment, have accounted for an outsized share of growth in the recovery. That's because traditional drivers — job gains, consumer spending and housing — have underperformed.

Fueling the June export pullback were declines of 9% in industrial machines and engines, 5.1% in semiconductors and 4.5% in computer gear — key categories that fed an export surge earlier in the recovery.

Although growth will likely slow, exports are not likely to crater.

European debt troubles that have darkened the economic outlook and contributed to stock market chaos should reduce U.S. shipments to the continent, Daco says.

But Troy Davig of Barclays Capital says fast-growing emerging markets account for a growing share of shipments. China, for instance, buys 7% of U.S. exports, up from 2% in 2000, while Europe buys 22%, down from 25%, IHS says.

Swonk, though, says developing markets have been big buyers of U.S. industrial parts and other capital goods, so drop in those categories may mean China's overheated economy is cooling.