Why are Americans putting off retirement?

The economic collapse that followed the financial crisis is causing Americans to push back the age at which they retire.

A new Gallup poll shows that the average age at which American retirees report leaving the workforce is now 62, the highest age since Gallup started tracking the issue in 1991. The age at which working Americans say they'll retire has also inched up in recent years, increasing to 66, from 64 a decade ago.

The findings lend credence to something that many Americans already know: The golden age for retirement is long past. After all, the average retirement age in the early 1990s was just 57, a time when more than half of Americans over 60 received income from pensions. With the recession and the housing crisis, Americans are less prepared for retirement than they were in 2007, the Center for Retirement Research found in December.

"Retirement age may be increasing because many baby boomers are reluctant to retire," Gallup said. "Older Americans may also be delaying retirement because of lost savings during the Great Recession or because of insufficient savings even before the economic downturn."

At the same time, the Social Security Administration has upped its full retirement age, which means that people born after 1960 won't receive their full benefits until they turn 67. That might explain why working Americans say they plan to retire, on average, at 66, or four years above the self-reported retirement age for currently retired people, Gallup notes.

"Today's workers are also less likely to have an employer-sponsored pension, and they may still be recovering financially from the Great Recession," the polling organization notes.

Surprisingly, one in 10 Americans between the ages of 18 to 29 say they will retire before they turn 55, which Gallup notes could be because they "may not understand the financial realities and challenges of funding retirement that middle-aged Americans are more familiar with."

The fact is that Generation Y -- or Americans between 20 to 29 -- aren't exactly ramping up their savings to prepare for an early retirement, according to a new study from the ADP Research Institute, which is part of the payroll service company ADP. Less than half of Gen Yers are setting aside money for retirement, and on average are socking away less than 5 percent of their earnings, the study found.

Despite age differences, a majority of those polled say they expect to retire at age 65 or older, although the oldest group surveyed -- at ages 50 to 64 -- were more likely to say they'd retire after they turn 65.

Given trends in the U.S. such as the shift away pension plans and the later full benefit age for Social Security, "the average retirement age and expected retirement age may converge as current workers retire later in life," Gallup notes.