American factories accelerated in August at the fastest pace of expansion since 2011, data from the Institute for Supply Management showed Friday.

The ISM purchasing manufacturers surveyed showed all six of the biggest manufacturing industries ramped up activity in August.

The monthly purchasing managers index rose 2.5 points to 58.8, reflecting employment rising to its highest level since June of 2011, an increase in production and rising inventories. Economists had expected a reading of 56.5. Any reading over 50 indicates growth.

Exports and new orders continued to show strong growth, although these slowed from July.

The Bureau of Labor Statistics said on Friday that manufacturing employment increased the most since 2012.

The sustained gains in manufacturing reflect rising consumer spending and business investment. The ISM number from Friday suggests that third quarter economic growth may be greater than previously thought. Some economists believe that the economy could be growing at a four percent pace right now.