The Chicago Purchasing Managers' Business Barometer soared to 66.2 in October from 60.5 in September, the National Association of Purchasing Management-Chicago said Friday.
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 60.0 reading for the index.
The increase brought the Barometer to its highest reading in a year.
"New Orders was the strongest component of the Barometer and increased sharply to 73.6, the highest level since October 2013," according to the release. "Production also strengthened further following a sharp decline in the previous month, and has been running at a firm pace for some time now."