CHICAGO (AP) — A rising share of older Americans is forgoing the concept of a traditional retirement at the age of 65, a trend that some younger workers aren't particularly thrilled to see.

A recent poll by The Associated Press-NORC Center for Public Affairs Research found that workers under the age of 50 were significantly more likely to view America's aging workforce as a negative development when compared with their older counterparts. About 4 in 10 respondents ages 18 to 49 and 44% of the youngest respondents ages 18 to 29 said they consider the trend to be a bad thing for American workers. Just 14% of those age 60 and over said the same.

"I don't think in things like IT and medicine you're as effective a worker (at 65 years old) as you are at 50," says Katie Otting, a 29-year-old living in Southern California. "If some 65-year-old is in a position that he's not ready to quit because he wants a better pension and there's someone else ready to take that job, they're not going to replace him."

An aging population, elevated health care costs and lingering financial uncertainty following the Great Recession all are believed to be contributing to America's steadily graying workforce. Nearly 20% of Americans over the age of 65 were employed or actively looking for work last year, up from less than 12% two decades prior, according to the Bureau of Labor Statistics.

But the increased prevalence of older workers has led some to believe seniors are holding back the country's economic momentum by remaining in the workforce. Men were slightly more likely than women to cite the aging workforce as a problem for U.S. workers (32% to 27. And about a third (34%) of more affluent respondents earning more than $100,000 annually said the same, slightly more than the 24% of those earning less than $30,000 who said so.

By contrast, about 6 in 10 Americans age 60 and over say the trend has actually been a good thing for the economy, compared with 3 in 10 Americans under 30 who think that.

About a third of Americans under 50 who have noticed the trend in their own workplace believe the aging workforce has negative implications for their own careers.

"One of the myths that's out there causing younger and older people to butt heads is the idea that 'Oh, it's because these older people are on the job preventing me from getting the job I want,'" says Steve Burghardt, a 74-year-old professor of social work at the City University of New York who thinks Americans are "looking for someone younger or someone older to blame" for inequality, job displacement and other economic problems.

Research is mixed on the aging workforce's overall impact on the U.S. economy. Adam Ozimek, a senior economist at Moody's Analytics, says his prior research efforts have suggested a growing population of older workers can slow productivity and ultimately hamper wage growth for the rest of the labor market.

But he says there's little evidence to suggest that the presence of older workers is "crowding younger workers out of promotions," noting that many of the workers who would naturally move up and replace positions currently held by baby boomers are not millennials but rather middle-aged members of Generation X.

"In anxious times, we look for scapegoats. And old people are a ready scapegoat, especially if you are forced out of having a public presence or are forced (out of a job)," says Ashton Applewhite, a New York-based writer and ageism activist.

The idea that older workers are keeping jobs away from younger Americans, preventing them from moving up the corporate ladder into higher-ranking, higher-paying positions, is not a new one. But economists say it doesn't have much basis in economic reality.

"The more of those seniors continue to work, that means they're also spending. And that spending helps build a rich economy that gives you jobs and lots of opportunities," says Andrew Chamberlain, chief economist at employment hub Glassdoor.

But Chamberlain and Ozimek say it might be easier to believe older workers are holding back their younger counterparts when looking at the economy on a smaller scale. One particular company, for example, may only employ one chief of marketing. Should that person choose to remain in the workforce until he or she is 80 years old, lower ranking employees may perceive a lack of upward mobility.

A comparable job may be ripe for the taking elsewhere, Chamberlain says, but it may be at another company or in another city that would require a move that many employees may be unwilling to make.

"They feel like their opportunities are only within that firm," Chamberlain says. "I think it's just simple confusion. I think people are mixing up (opportunities) just inside one company versus the overall job market."

Meanwhile, many older workers are coming to terms with the fact that they'll need to remain in the workforce to keep their heads above water or maintain their current lifestyles. Mitch Rothschild, 61, lives and works in New York City and says he expects he is "probably going to have to work until I die."

He says the aging workforce is less of an economic problem and more of a financial reality to which workers of all ages need to adapt.

"Hey, look, I wished I'd been skiing in the Alps since I was 40," he says. "But you think I'm going to stop working a year from now and rely on Social Security for the next 20 years? No."

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EDITOR'S NOTE — Andrew Soergel is studying aging and workforce issues as part of a 10-month fellowship at The Associated Press-NORC Center for Public Affairs Research, which joins NORC's independent research and AP journalism. The fellowship is funded by the Alfred P. Sloan Foundation.

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The AP-NORC Center survey of 1,423 adults was conducted by The Associated Press-NORC Center for Public Affairs Research with funding from the Alfred P. Sloan Foundation. It was conducted Feb. 14 to 18 using a sample drawn from NORC's probability-based AmeriSpeak Panel, which is designed to be representative of the U.S. population. The margin of sampling error for all respondents is plus or minus 3.7 percentage points.

Respondents were first selected randomly using address-based sampling methods and later were interviewed online or by phone.

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AP-NORC Center: http://www.apnorc.org