The Chicago Business Barometer rose to 58.3 in April from 57.7 in March.
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 56.5 reading for the index.
“Demand continued to gain ground in April, rising for the third consecutive month. New orders rose by 5.5 points, to touch almost a three-year high,” according to a release. “Off the back of two consecutive rises, Production dipped slightly. The indicator fell 2.2 points to 59.5 from 61.7 in March. Order Backlogs contracted for the fifth consecutive month, although at a much faster rate than in recent months. Suppliers took longer to deliver key inputs, with the respective indicator 1.6 points higher at 56.0 in April.”