A closely watched measure of manufacturing activity in the U.S. reached a 13-year high in September, as strong demand and order growth rode out a severe hurricane season.

The Institute for Supply Management said Monday that its index of manufacturing activity climbed to 60.8 last month from 58.8 in August, hitting its highest reading since May 2004. A reading above 50 indicates sector expansion as measured by factors such as sales, output and hiring.

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