Unemployment among construction workers dropped to 13.3 percent as the industry added 26,000 jobs in August and September, according to data from the Associated General Contractors of America.

The increase is the first significant movement in employment since February and reflects new demand for nonresidential projects, association officials said.

“These numbers give us a taste for how investing in construction activity can really boost overall employment figures,” said Stephen E. Sandherr, the AGC’s chief executive officer. “However, the real question is whether these numbers are an anomaly or the start of a positive trend.”

Sandherr said that the industry’s 13.3 percent unemployment rate was an improvement from the 17.2 percent rate of a year ago, but it is still far above overall national unemployment rate of 9.1 percent. He said much of the decline in the construction’s unemployment rate was caused by workers leaving the industry rather than new jobs.

“With private sector demand inching back up, the construction industry is finally on the brink of recovering from years of hardship and job losses,” Sandherr said. “If Washington continues to cut infrastructure funding instead of addressing out of control entitlement spending, the industry will lose whatever momentum it picked up in September.”