The Chicago Purchasing Managers' Business Barometer fell to 60.8 in November from 66.2 in October, the National Association of Purchasing Management-Chicago said Wednesday.
The data is compiled on a seasonally adjusted basis. An index reading below 50 signals a slowing economy, while a level above 50 suggests expansion.
Economists polled by Thomson Reuters predicted a 63.0 reading for the index.
The decline took back most of October's "sharp increase," as all five components of the Barometer declines.
"In spite of the slowdown, orders and output continued to expand at a healthy pace. Production, New Orders and the Barometer itself have been running above 60 for four months in a row, suggesting continued firm growth in the US economy," the group said in a release.
