The Institute of Supply of America said Monday that the industrial PMI rose to 60.8 points last September, from 58.8 points a month earlier.
Analysts had expected the PMI to reach 57.9 points.
The new orders index rose to 64.6 points last month from 60.3 points in August.
In a separate release, a survey by Market showed the final reading of the US manufacturing PMI rose to 53.1 points in September, against a preliminary estimate of 53 points, compared to 52.8 points in August.
The greenback rose 0.6% against the euro, with the single currency heading down to $ 1.1743 at 3:15 pm GMT.