NEW YORK --- Signs grew that the economy could turn even weaker in 2009, as an index of December manufacturing activity sank to its lowest point in 28 years. Every corner of the sector was down, from bakeries to cigarette-makers to aluminum smelters.

The Institute for Supply Management, a trade group of purchasing executives, said Friday that its manufacturing index fell to 32.4 in December, a greater-than-expected decline from November's reading of 36.2. Wall Street economists surveyed by Thomson Reuters had expected the reading to fall to 35.5.

Components of the index hit historic lows. New orders fell to their lowest level on records going back to 1948. Prices fell as the number of respondents saying they had paid more in December than in November sank to its lowest monthly reading since 1949.

A reading below 50 for the overall index indicates contraction. The index, based on a survey of the institute's members, has fallen steadily for the past five months.

December's reading is the lowest since June 1980, when the economy was near the end of a six-month recession.

If December's rate of manufacturing activity were to persist for 2009, the nation's gross domestic product would show a 2.7 percent contraction, according to Norbert Ore, the chairman of the group's business survey committee. GDP, the broadest measure of economic activity, decreased at an annual rate of 0.5 percent in the third quarter of 2008, according to the Bureau of Economic Analysis.

Only three recessions in the history of the index have showed weaker manufacturing readings, said John Ryding, of RDQ Economics. Those recessions were in 1948 to 1949, 1973 to 1975 and 1980.

The U.S. weakness is part of a worldwide slowdown. China's manufacturing sector, which accounts for 43 percent of the economy, contracted for a fifth straight month in December. Singapore said its economy shrank in the fourth quarter, and South Korea said its exports fell 17.4 percent in December. With European manufacturing indexes also dropping, "the case for a massive global fiscal stimulus continues to grow," Mr. Ryding said.