The Federal Reserve Bank of Philadelphia says its index of regional factory activity ticked down to 5 this month from 5.2 in February. Any figure above zero indicates expansion.
It was the fourth straight decline after the index reached its highest point in more than two decades in November. It follows a similar survey from the New York Fed earlier this week that also found slightly slower factory growth.
A measure of hiring slipped but remained in positive territory, a sign factories are still adding jobs.
The survey covers manufacturing in eastern Pennsylvania, southern New Jersey and Delaware.