The increase continued a pattern shown in the past six months of weak job growth and a rising unemployment rate compared with year-earlier levels. Last week the department said the Island had 9,100 more jobs than a year earlier, an increase that was largely due to seasonal factors.
The department uses year-over-year comparisons because local data aren't adjusted to account for monthly, seasonal fluctuations in employment.
The latest jobless data contrast sharply with the 4 percent rate, considered "full employment," for September 2007, three months before the recession officially began. Though the downturn ended in June 2009, the rate in every September since then has remained stuck above 7 percent.
The number of unemployed workers in September rose to 107,400, up 4,800 from a year ago. At the same time, the number of employed residents rose to 1.355 million, up 6,700 from a year ago.
The rising number of unemployed may indicate that more discouraged workers are resuming their job search.
"Some of them find jobs; so employment numbers go up," said Prof. Panos Mourdoukoutas, chair of the economics department at LIU Post in Brookville. "Some of them cannot find jobs and are still looking, and that pushed the unemployment rate higher."
Job growth just hasn't been "robust" enough to reduce the unemployment rate, said Shital Patel, labor market analyst in the department's Hicksville office.
"The bottom line is that it's harder to get a job on Long Island than it was before," she said.
Frank Guglielmi, 38, of West Babylon has been looking for employment since February, when he lost his computer-network analyst job at a Melville credit-card processing company. He had worked there for six years.
His wife works -- she is a nurse -- but having just one income means "it's kind of tough to make ends meet," Guglielmi said. The couple and their three children now eat out about every three weeks, compared with once a week when Guglielmi worked.
He estimates he has sent out 50 resumes. Employers often say they will get back to him.
"But then you don't hear anything," he said.
Hempstead Village had the highest unemployment rate on the Island at 9.1 percent. North Hempstead Town had the lowest, 6.1 percent. Among counties around the state, Tompkins, home to Cornell University, had the lowest, at 5.7 percent.
New York State's unemployment rate was 8.2 percent last month. The national rate was 7.8 percent. Both rates, like local data, aren't seasonally adjusted.