Manufacturing activity in five Midwestern states fell 2.3% in January from a month earlier, dropping to its lowest level since October 2005, according to data released Monday by the Federal Reserve Bank of Chicago.

The Chicago Fed Midwest Manufacturing Index - a measure of manufacturing output in Illinois, Indiana, Iowa, Michigan and Wisconsin - fell to a seasonally adjusted level of 102.1 in January, from 104.6 in December. The Chicago Fed said in a press release that the December figure was revised from a previously reported 104.5.