The Institute for Supply Management's US manufacturing index rose to 55.6 in July from 53.3 in June, compared with expectations for a smaller increase to a reading of 53.9 in a survey compiled by Bloomberg.
This is the highest reading since May 2022, ISM said.
There were increases in the readings for new orders, order backlogs, production and employment, but decreases in readings for inventories and prices.
"In July, US manufacturing activity remained in expansion territory, growing at its fastest rate in more than four years," said ISM Manufacturing Committee Chair Susan Spence.
The monthly national manufacturing reading from the Institute for Supply Management is reported as a headline index, with readings above 50 indicating expansion and those below 50 indicating contraction. Component indexes measure new orders, production, employment, and prices.
An increase in the index further above 50 is considered a sign of a strong US manufacturing sector, generally a positive for manufacturing industry stocks. However, if that strength comes with rising input prices due to shortages, that could be a negative for stocks as well as bonds.