U.S. employers added 248,000 jobs in September, allowing the nation to reach an unemployment milestone.

For the first time in six years, the unemployment rate dropped below 6 percent to 5.9 percent, the U.S. Labor Department reported Friday.

Five years ago, there was another milestone. In October 2009, as the nation struggled to escape the grip of the recession, unemployment reached 10 percent, the worst rate in a quarter-century.

Jobs were added in every sector in September - manufacturing, health, education, business, finance, information technology, retail, and government.

In construction, which had been hammered during the recession, payrolls grew to nearly 6.1 million, the highest employment since May 2009.

Strong growth in motor vehicle manufacturing meant more hiring in factories. Portending a good start to the holiday season, retail was up from last month and last year.

Hiring expanded in architectural and engineering services, meaning future job-generating projects.

Even though 5,240 jobs were lost in Atlantic City's casinos, the leisure sector overall added 33,000 jobs nationally. States are hiring, bringing public sector employment up, despite declines on the local and federal level.

The U.S. Labor Department also revised numbers from July and August upward, adding 69,000 to the 354,000 jobs already reported.

"Six years after the near-collapse of the U.S. economy, we have come a long, long way," U.S. Labor Secretary Thomas E. Perez said in a statement.

Given the news, the reaction from economists should have matched Friday's euphoria on Wall Street, where the Dow Jones average jumped by 208.64 points and all 10 sectors in the S&P 500 ended higher.

But economists and others noted three disquieting issues - wages have failed to increase in response to a tightening labor market; the ratio of people who have or want jobs in a proportion to the total working-age population is stagnant; and long-term unemployment persists.

"It's become clear to us at this point that these people are invisible," said Cheryl Spaulding, cofounder of Joseph's People, a network of support groups for the unemployed based in 13 churches in Chester, Delaware, Montgomery, and Berks Counties.

In September, the number of unemployed people decreased to 9.3 million. Of those, nearly three million or 31.9 percent, are long-term, meaning they have been out of work for more than six months.

Through its website, www.josephspeople.org, Spaulding's group is surveying the longterm unemployed and hoping to learn more to better advocate for them.

Looking at more than 50 responses received so far, Spaulding said: "Most of them are 45 to 65 years old. They are equally male and female. The level of their education is higher than I thought. There are a lot more degrees there than I thought."

Many aren't working, which surprised Spaulding, until she recalled comments made by unemployed people attending the group's meetings.

"You hear, 'I can't get a job at the Home Depot. Everywhere I turn, I'm overqualified.' And when you look at their degrees, they are correct. They aren't going to get hired," she said.

Findings from Spaulding's informal survey were validated by more thorough research released in September by the John J. Heldrich Center for Workforce Development at Rutgers University in New Brunswick.

Fifty million people - nearly one in five workers - were laid off in the past five years. And more than one in five of those workers never found a job. Four in 10 of them took seven months or more to find work, the study found.

Significantly, among the current long-term unemployed, only 38 percent have managed to qualify for the most well-known safety net for the jobless, unemployment benefits.

"That never was a universal program," said Rutgers public policy professor Carl Van Horn, the Heldrich Center's director and the lead author of the report titled "Left Behind: The Long-term Unemployed Struggle in an Improving Economy."

"You only qualify for it if you have stable employment and you earn a certain amount of money," Van Horn said.

For example, he said, some of the 5,240 casino workers who lost their jobs at Showboat, Revel, and Trump Plaza in September may not qualify for unemployment benefits. If they were "part-time workers making $8.25 [per hour], they were probably not earning enough to qualify."

"There are many people who never get unemployment benefits," he said.