Production at US factories last month fell by 2.8 percent, the largest decline since December 1974, according to a report released today by the Federal Reserve. The decrease in production at factories, mines and utilities far exceeded analystsÔÇÖ forecasts and followed a 1 percent decrease in August, the Fed said. The Fed said that production fell 6 percent for the third quarter, the largest drop since 1991, almost doubling the 3.1 percent drop for the second quarter.